The standard explanation is that gay men started idolizing them because they represented images of non-male power. Since gay men were viewed as less-than-men, identification with powerful female images was easier to reconcile with their deviating sexuality. Add to that the rise of fan magazines (and later gossip/scandal sheets like Confidential) detailing the personal lives and tragedies many of these women faced, which mirrored the drama some gay men had in their own lives, and the identification becomes stronger.
Diva worship kind of faded starting in the mid-70s with the decline of disco and the rise of clone culture and continued to fade through the 80s (the late drag legend Charles Pierce observed that there weren’t any new female stars worth impersonating, variously offering Phoebe Cates, Jill Clayburgh and Tori Spelling as evidence), with upkicks coming with the rise of Madonna.
Now VH1 does specials and declares pretty much any random singer who can hold an ear-piercing high note for 8 seconds a “diva” (yes I am looking at you Celine Dion) and the concept has been cheapened.
I think a lot of diva worship these days is tinged with irony. It’s less about direct identification with the diva and more about admiration of their ballsiness.
My nominee for #1 gay icon of all time is Judy Garland. The reasons why would fill a book, in fact have filled several which reside on my bookshelves. She was IMHO the best female entertainer ever, if not simply the best entertainer period. Her achievements would be amazing without the personal swamps and minefields she navigated throughout her life. Taking those into consideration, her acheivements were, with no exaggeration, the stuff of legend.
One person I would strike from the list is Princess Diana (unless you mean Wonder Woman of course, in which case you go!). She wore nice clothes and she held AIDS babies when other famous people didn’t. That’s about it from her on the gay front. No gay icon she.