My position, strictly speaking, is that anonymity is generally permissible. If you want to try to remain anonymous, that is in many cases fine. But it is also quite difficult, particularly in the face of determined investigation, and is therefore rather unrealistic. Unless you really know what you are doing, your attempts will fail as soon as someone really cares about finding out. This makes combining anonymity with any sort of public prominence or celebrity status a particularly bad fit, because plenty of people care about knowing all sorts of details about celebrities, so there is plenty of reason for both amateur snoops and professional investigators to go looking.
I don't find your example of celebrity pseudonyms particularly convincing. These are simply terms of convenience, part of crafting a public image. They are not true attempts to hide anyone's identity. Pull up the wiki page of most any celebrity that goes by a stage name, and you'll find their real or original name.
https://en.wikipedia.org/wiki/Tupac_Shakur