I don't do much mountain biking, but I have clipless pedals on my old hardtail, too. When I ride without clipless, I have to constantly remember not to push too hard and be careful, lest my foot slip off. With clipless, I clip in and no longer have to think about it.

I don't really care what other people use. I'll stick with clipless, you can stick with flats or whatever you use, it's fine with me. I use electronic shifting on my road and gravel bikes, and disc brakes on the gravel bike, and I know some people hate both of those things, too. Personally I really like both, but if others still want to use cable shifters and rim brakes, that's fine with me.