In the ‘olden’ days, we used multiple pages because our system did not handle aliases and credited as. We used (as example) a page titled as an artist’s legal name for writing credits, and other pages for performance credits with their stage name.
We can now handle these all on one page.
But, yes, there are times when someone can still have the “legal name / performs as” relationship. There is no limit as to how many pages someone can have. But, it boils down to if they need multiple pages or not.
And THAT is the million dollar question.
Since I disagree with much of the scenario (old rich white guy set in his ways with a 1920s mentality), it was explained to me as -
If you think of a DJ as a band with one member instead of being just a single person.
So, as example - John Smith is a single person. He was a member of many bands. Band X doesn’t play music from the Band Y just because John was a member of both. You’d have 3 pages, one for John and one for each band and John would be listed as a member.
But, if Band X changes its name to Band X2, it is still the same band they just have a new name and will play the same songs. Band X2 would be the same page as Band X, we would just use various site features to credit them as Band X2 when needed.
With DJs, instead of being a band with members, it would be a person with a “legal name” link.