Or maybe there's just people who watch lots of game and are not willing to just stick to the only argument you seem to have to dismiss pretty much any dissenting opinion, meaning "you don't want the best DM in the world??? You're a moaning cnut!".
I watch pretty much every Real Madrid game, and Casemiro did struggle a lot when the team wasn't clicking under Zidane or at the beginning of Carlo's come back. It was bad, and when I mean bad, I mean "can barely do a decent control" bad. If you don't believe me, go watch the games against Valencia or Villareal at the beginning of the 21/22 season when Carlo had to take him out because he truely was terrible.
So please allow some of us here to have doubts that he'll fit right in and do his "best DM in the world" thing when he shows up in a disfunctionnal team in a different league after a decade playing with 2 of the very best midfielders of the decade in a well oiled machine.