The Prom very much ISN'T a musical about the lesbians, though. They're central to the plot, but ironically enough, despite It's Not About Me, the main character is 100% Dee Dee. I think not advertising it as "a lesbian movie" was thus the right call, there's already complaints about Emma and Alyssa not getting enough screentime, imagine what that would've been like if they tried to go "and they're the main characters" It's LGBT-themed, but Emma and Alyssa are supporting roles.
I kinda agree with what you're saying, the Broadway musical was promoted like that and they did get some backlash, because it is true that both the broadway actors AND the lesbians are the main plot point. However, Emma is not a supporting character, Alyssa yes, Emma no. Caitlin took the last bow on Broadway and she was nominated for the Tony in the lead actress category.
I really would've wished that netflix would've advertised Emma's story a bit more. Especially on their twitter accounts it always feels like both Emma and Alyssa are an afterthought, that it's always merryl streep here and merryl streep there, when I really think young closeted lesbians / wlw's are the ones who need this film the most, certainly more than cis white middle aged merryl streep fans ya feel me.
It is true that had they only advertised the lesbian storyline or mainly the lesbian storyline like the Broadway show did at the beginning, they would've caught backlash. But in the end they caught backlash anyways, and as a lesbian myself, watching the promo accs on netflix, I felt like a commodity, an afterthought, when Emma, a lesbian, is a main character (not the main character but one of them, Dee Dee and Barry being the other two main character)

















