The problem is that there are too many prawn sandwich fans there, and people who go 'to be entertained' (and see a United win), as if they are at the theatre.
That's what the PL have turned their top end game to, pure voyeurism. Only those clubs where more regular fans go - working class (and others) on which the sport was founded - retain the atmosphere. It ends up being smaller, unsuccessful clubs, or niche areas like Liverpool and Leeds. Anfield can be really quiet in regular league games too, saying that.