Good points. I agree with you in principle about sharing gear to cut weight, but I don't actually do it when I meet up with my buddy Mike.

We tend to take solo trips together, because we both like to play with our own toys. Also, it gives us the option of hiking together but camping separately (for example, I might want to be down by the stream, but he might want to head up to the ridge top because of the full moon.) Also, even though we've been doing this for close to 20 years together, I'm still not entirely convinced I can trust him to remember his half of the shared gear. (But then, I'm still not convinced my daughter and son-in-law can be trusted with small electrical appliances, let alone my grandkids. )

If you're going with a group, absolutely share gear. But, there's nothing inherently wrong with being self-sufficient inside the group, either. Again, it comes down to preference.