Everyone today seems to regard a tent as de rigeur, but I backpacked regularly for well over a decade before I owned a tent for regular three season backpacking. I did have a surplus Army mountain tent (heavy!) for winter outings, but we regularly used tarps. My need for a tent grew in later years when often me and my partner desired (ahem!) some privacy. Six pounds was a small price to pay.
When I set up my tarp and hammock, people will claim they need a tent to keep out bugs. I have a full zip bugnet on the hammock and the times I have been bugbit while tarping on the ground - once, out of more than 20 tarp trips now.
The funny thing to me is that on one trip, a guy was harping away about bugs and needing a tent, you're gonna be cold and bugs will get you, yadda blah blah, and an hour later he was yelling about all the ants in his tent. Park your tent on an anthill or three and leave the zipper open and guess what! Being complacent and neglecting appropriate site selection only shows how even a tent isn't the bombproof protection people seem to think it is.