I don't buy the blanket anonymisation for the safety of creatives explanation for one second.
MTG credits artists, video games can do it (when a company is not using "removal from the credits" as a cudgel to keep workers in line), movies too. Essentially every major entertainment industry does.
Those are all also much bigger industries than
GW that are also highly collaborative when it comes to the process. They also have that type of obsessed
fans that
GW has in numbers that dwarf
GW. If somebody wanted to stay anonymous then that should be their decisions (see solutions like
Alan Smithee for movie directors), not
GW's, when it comes to credits.