"Ally" is just another in the long line of useless SJW concepts. How about just not being homophobic or sexist? But no, that's not deemed sufficient. Privilege is basically the SJW take on Original Sin, and declaring yourself to be an ally is like self-flaggelating yourself into repentance.

You don't need to ally yourself with every gay person to not be a homophobe, and you don't need to ally yourself with every woman to not be a sexist.

The people who want "allies" tend to be surrounded by unquestioning fans and tend to get their panties in a bunch when faced with actual criticism, deserved or not. If you believe that any criticism you receive happens because you are gay or because you are a woman, then "allies" are the only people who won't upset your delicate sensibilities.