Let’s simply note a few other categories that exist: romantic suspense, paranormal romances, inspirational romances, Amish romances (which are, I think, sufficiently distinct from inspirational romances to count as their own field), LGBTQ romances, military-themed romances (which often overlap with romantic suspense, but not always), historical romances that aren’t set in England’s Regency period…
There’s a crap ton more. My wife’s Starstruck series is young adult science fiction romance. She also has a time travel novel where a heroine trades places in time with her own great, great, great, great grandmother with the story following both heroines equally as they adjust to their new times and fall in love with men their prior selves despised. Where does that fit in Mr. Gottlieb’s convenient pigeon holes?
The haughty male reviewer condescending to declare that this “female fiction is all the same” is tired trope in itself. There’s nothing new in that.
Here’s the thing. You hear much less of that kind of talk about popular men’s fiction, such as Westerns or war novels. Tell much the same story, except throw in a romance, and suddenly the critic solemnly speaks from on high to say “it’s all the same.”
This reviewing trope of women’s fiction is really as much about the sexism of male reviewers as it is anything else.