with simplex you are simply responsible for your own backups. And bigger groups are in the roadmap: https://github.com/simplex-chat/simplex-chat#roadmap

captchas on matrix? since when? never seen it on any of our instances or clients. btw I wouldn't recommend ever connecting to matrix.org, use a self hosted instance, not that hard

this is a great post btw, I agree the perfect messenger app does not exist (yet)

I would love for it to be briar due to their mesh networking feature, but the app does need more work.