its because compared to other (older) solutions, it's a pain. you gotta download the APK of the manager, then it's asking you to root your phone or give it an APK of the app you're trying to crack, so I guess I gotta go hunt for a YouTube APK?
too much work when I can just stop watching YouTube, and for the one video per week that's unavoidable, make do with my half-brokem version of YouTube Vanced that's still on my phone.
Filemanager +
Has everything I need, good UI, good quick access to commonly used folders and SD card, good file manipulation options.
or you could just look at the "Local" and "all" feeds, then you'd see everything's that's going on and can join communities you like organically. imho much better than being forced into random communities you don't care about, and at the current user level it also doesn't make sense to join a bunch of half-empty communities where nothing's happening while the full instance gives you just the right amount of content and interaction.
with liftoff you don't even need to be on said instances yourself, just add the five or so biggest servers to the list and browse global/all, then you're getting nearly everything that's happening on the Lemmy network right now, and can then pick your communities accordingly.