"People are frustrated because they come to the game with a strong understanding of how 5e works, and then that's changed in a way that they can't make sense of and makes the game less fun for them."
Isn't that the definition of "it's different, so it sucks?" I feel like tons of things from 5e are still here, too. Someone who's never played dnd will still be playing catch-up to the players that recognize all these features, no?
No. Differences in and of themselves don't suck. Differences that don't make sense and don't make for a better experience suck.
