I suspect people get caught up in the gendered aspect of it. Which, yes, abuse happens more commonly along gender lines, but a lot of times it's more about relationship dynamics, intimacy, and parties trying to exert control over each other whether they're same sex or different sex, sexual or platonic, romantic or familial.

(cf. the post about the woman whose mother screams at her and is trying to control her by making accusations at LW about LW's kids.)