Leo Messi is without a doubt the greatest player to play the game, just a Total Footballer in the Cruijff mold... but no player should be above the club. Without a doubt Lucho is a crap manager but any manager who comes in either abides by Messi or faces the ax. That is not good for any club. There were stories of dissent even when Pep was the manager and that's just ridiculous.
Most of this is all speculation and could be completely false/BS but if there's any truth to it then it's not good for us in the long-run. We admire managers like Cruyff, Pep, LvG, Rijkaard but I think we could learn a thing or 2 from Sir Alex. If a player got too big for his boots, he was out. The team & club is what matters over any 1 player. Pep easily could have continued had he had a board to back him completely after all he delivered in 4 years.
I also think Messi needs Barcelona as much as Barcelona need him. What other team could he slide into today and have the same impact? PSG? Chelsea? Due to their playing styles and current roster I doubt he'd work in either team or league.