Your statement that "a city that has a large group of gay men doesn't necessarily have a large group of lesbians" is accurate, but this is a bad piece of evidence to cite in favor of it. Almost all cities with large LGBTQ+ populations have far more bars and clubs targeted at gay men than at lesbians.

San Francisco had a few lesbian bars a few years ago, all of which have since closed. That pattern - lesbian nightlife disappearing - is pretty consistent across other cities that have large LGBTQ+ populations.