It’s essential – you need to memorize everyone on these lists, for the same reason you do it with actors and actresses, and anyone else for that matter.
Go through this list and try to count the number of singers who appeared on American Idol.
We are not impressed that Melissa Etheridge or k.d. Lang was the first that came to your mind.
I believe the criteria to make this list is to 1) be a musician and 2) have at least one sexual encounter with the same sex.