Introduce a company style that the artists are forced to use! No individual styles, every character should look the same no matter who draws him/her, screw the artsy stuff. You want to draw in your own style? Create your own stuff at your own company.
Because only the annoying fanboys who are the vast, vast, vast, vast
minority of the audience gives a flying fuck about who drew what. The equally vast majority
, however, just wants to enjoy the stories and not have to withstand an art style that looks okay one month but then spontaneously transforms into some goofy ass shit that makes them not even want to keep reading the next.
That's probably why.
It also has the additional perk of greatly decreasing the chance that any one artist can have a stranglehold on a comic book by taking their sweet ass time getting the job done. If one decides to act that way, can their ass and let any number of other artists step in all without the readers being the wiser.