It’s not that it’s bad per se. The whole federation thing is confusing enough that it’s a barrier to entry. There’s also the fact that change is hard. Mastodon has a different interface, with the associated learning curve. Beyond that, it’s not just having a certain number of celebrities/etc, but the right ones. That leads to a chicken and egg problem for a lot of users. Eventually enough people would sign up (and content creators posting to both) that it would trigger a mass migration, but that has not happened yet.
So, after all that, most users decide that Twitter is ok enough for now.
As awful as that is, the design of those dumpsters will always lead to this. To put the bag in, you must hold the lid open well above your head (and higher than many people can reach) while holding a heavy bag of trash, then lift it even higher to get it in. If you are smaller than average (e.g. a child), physically disabled, or just not an able-bodied adult, that becomes impossible