I think the issue is that a gay man or a lesbian does not yet know if it is safe to even have those normal conversations with some person they are just getting to know. If they're asked a question that would lead to "I was at lunch with my boyfriend/girlfriend", they might get a homophobic response.

Directly coming out to you, when they are comfortable and emotionally prepared for it, is a way to avoid a traumatic reaction during normal conversation.

Beyond that, when you've been forced to repress some part of yourself due to social expectations, it can be a big relief to be able to specifically tell people about that part of you, rather than just letting it come up obliquely during conversation when you happen to refer to a same-sex partner.

I really do appreciate your response and glad I got through. And yeah, sex is pretty foundational to society. As I get older I see that more and more. Just know that the next time a person comes out to you explicitly and says "I'm gay!", they are not trying to awkwardly insert their sex lives, they are doing the best they could to get through a potentially difficult moment with a person they had to come out to. This is especially true when a person is at the beginning of their journey to accept themselves and find acceptance in others.