I don't know when this tag was created, but it seems to make little sense. Workboards should be used for this purpose.
It's enough for the user to be conistently harassed by the "MediaWiki core" vs. "MediaWiki Core [team]" dilemma when choosing projects, no need to also add a "MediaWiki Core vs. all its pseudo-synonims" dilemma.
I don't know when this tag was created
See T78822
Workboards should be used for this purpose.
Please feel free to elaborate in T78822 why you think that the approach proposed by you is sufficient. Many folks who ask for creating those projects did not consider workboards sufficient.
Your audience for discussion is in T78822. I'm marking this ticket as declined to not scatter the same discussion and repeating the same arguments in two differrent places.
I'd be cool with that. Renaming our MediaWiki-Core-Team tag to MWCore-Team wouldn't bother me either. Do we just need team level consensus?