It's not that City have no history, it's that they're a relatively small club posing as Real Madrid. This is especially irritating because their fans have always had this ridiculous exceptionalism, and they now feel vindicated by an accident. A couple of eras of success and and a moderately-sized fanbase describes maybe dozen clubs in English football. Manchester City were on a par with Wolves, Derby, Forest, Blackburn, Preston, Burnley and so on until they won the lottery twice in the 2000s. The accurate way of putting the 'no history' charge is that the current City have no 'history' because there's essentially no direct connection between the proud and storied history of Manchester City Football Club and the current institution, which is entirely the creation of a few very rich men.
History is all about narrative, and City are the footballing equivalent of reading the first 343 chapters of War and Peace and then finding the rest of the book has been replaced by Katie Price's autobiography. Their owners essentially have a millenarian character, rendering everything that came before meaningless, and subsequently any footballer willing to play for them can be seen to be betraying the whole idea of history in football.
Put bluntly, ADUG are the Khmer Rouge of football, sort of.