In no particular order:

I have helped anyone in need, by making suggestions and offering food, water, use of a filter, or anything over the counter - I do not tell people what to do unless I perceive imminent harm. The gent lying prone by the trail with no water left in his Camelbak, no food, no supplies, red as a beet, gasping for air, telling me he had diarrhea for three days before trying to hike Half Dome was told by me under no uncertain terms to TURN AROUND AND GO TO THE MEDICAL CLINIC. (He was not, by the way, a member of our group.) When the leader of his scout group arrived I told him the same thing. He was given a little water and some food by my group, and the leader of his group was left to walk him out, go for help, whatever. They were a mile and a half from a table staffed by Yosemite staff with radios. If he had been unconscious or otherwise non ambulatory I would have sent someone myself, preferably someone who runs as well as hikes.

The safety of groups lies in not being out there alone and no one keeping track of you or able to catch you when you are showing signs of dehydration or hypothermia. All members of our groups are expected to carry adequate gear/provisions for themselves plus a map. This is explicitly stated along with recommendations that they tell someone where they are going - what if the entire group vanishes? Specifics about the individual hikers need to be communicated by their chosen responsible parties to the authorities. There is no way I am going to be able to collect all that myself and if I am on the hike I couldn't provide it anyway. Every hike is a different group of people.

The only problems we have had are occasionally misplaced (not quite lost, just disoriented for a few minutes) people, and the more frequent "I don't know my limits yet but I'm positive I'll be okay" newbie having either heat exhaustion, or elevation issues. There are a few organizers in the group who explicitly say "I can't deal with slow (mentally or physically) people" and screen people pretty carefully before saying they can go on the event. There has never been an instance where someone has been refused help when it's needed, and more than once someone in the group has walked with an ill person back to the car.

I receive consistent positive feedback that my trip descriptions provide accurate ratings of trips, and I always link to safety information, gear lists, and weather reports when setting up the trip so people understand how to prepare even if they have never been hiking. This has helped reduce the number of gimpy hiker issues significantly.

The group is not really intended to provide people with hikes - it's intended to provide hikers with opportunities to meet people who hike, resulting in a pool of people with whom you can go hiking outside the group. In that respect it's been mostly successful.

On the surface it doesn't sound like it would work out. For some people it doesn't, but to an extent you need to be outgoing enough to "interview" other hikers as you participate and make friends for it to really pay off. 95% of the folks who show up are responsible, friendly, honest and pretty darn cool. The other 5% gradually drop out as they realize I'm not going to stop asking them to be responsible for themselves, not going to be their tour guide, not going to let them play power/control games (I screen organizer volunteers, my criteria are "good communication skills, good organizational skills, stable personality and some hiking experience in the local area") and I will suggest people away from hard hikes when they can't do short, moderate ones. (I tell them they are perfectly within their rights to do anything they want any time, but that this hike is probably not going to be enjoyable for them because it's more climbing/miles than this other hike they didn't do well on. Part of the problem some folks have is the inability to understand the elevation gain/length they are capable of managing.)

Two civil attorneys later, and after many long conversations with people more experienced than I with organizing outdoor activity groups, including some Sierra Clubbers (I have many in my hiking group who also are part of the local chapter and are or were hike leaders for them), I am left with the following:

1. Telling someone what to do and how to do it and when to do it makes you liable for the outcome. Choose carefully what you tell people to do. Waivers hold up in court about half the time.

2. Suggesting to people and providing information doesn't make you liable.

And from my own organization of hikes over the past four years:
1. People lie - to themselves if not to you - about their abilities.
2. People with mental issues (if not an official diagnosis then some social malfunction impacting their ability to make friends) are frequently advised to join activity groups to meet people - I've done this too (but I don't mention my group when I do it!).
3. People surprise you - overweight people can show great stamina and joggers, runners, bikers, and gym rats can totally suffer while hiking. Wives carry half their husbands' gear sometimes, or vice versa. Kids have the capacity to outhike the most able 20-something sometimes. People defy categories and stereotypes.

I am trained to do assessments of suicidality and diagnose mental health disorders. I have had one hiker, who struggled to carry his pack a mere six miles and less than 500 feet of gain, express a wish for someone to shoot him. I walked away - that is not something I do for people who are not my client, for a variety of reasons, and I would walk away again. My liability policy will not cover any missteps made randomly attempting to treat people who have not come to me for treatment. He did make it out - I carried some of his stuff for him as did other group members, it took four of us with 50 liter packs to carry what was in his pack. He hasn't tried to backpack again and last I heard he is following dr orders not to carry more than 15 lbs in a pack (he had 70+ lbs, he received those orders before he went on the backpacking trip, and the experience radically changed how the group organizes backpacking trips).

I make no claim to expertise however often people in the group label me an expert. People have told me they trust my judgment, my navigation skills and my expert opinion (whatever that means) - I will tell them that backpacking is like anything else, you have a set of expectations and beliefs that work for you, and you make your own decisions about it based on your experiences. My choices are my own and no one else's - there is a general fund of knowledge on safety and first aid skill building, present in many books on the subject and on many websites in articles about backpacking. Beyond that what you take and what you do is a matter of where you go, when you go, and how comfortable you are with your own skills and gear - your choice. No one really likes that answer. Everyone wants a backpacking kit ready made for them and not to have to think about it that much.

Most if not all of my tactics in organizing are based on experience, knowledge of group dynamics, on-the-fly assessment (in my head) of the mental status of the individuals in front of me, and a huge amount of observation of others.

I still organize hikes and still enjoy it. Just like I still work with mentally ill and substance abuse clients, and still enjoy it. Hiking is my healthy outlet because there are still more sane people in my groups than there are unreliable, medically compromised or mentally impaired ones. The majority of the work involved in organizing a hike is in writing the description and posting it on the website, then occasionally sending an email. The rest of the experience is the reason I do it.

I do not require anyone to be tough. Just aware, adaptable and responsible.

335+ outdoor events later we have had positive event reviews 98% of the time.