a het relationship that can happen only when the m/m (or f/f) element is removed seems to be far too frequent in fiction, and it makes me really sad (and angry too, when I have enough spoons...)

True, and fair! There's a lot that could be be written about the conflict between friendship and 'friendship' and (m/f) romance in fiction pre-acknowledgement of same-sex relationships—it seems to turn up an awful lot as an... uncomfortable element in stories, perhaps in more than one way.

they kind of hijacked and took advantage of other's people only way to communicate, if that makes sense?

Yeah, it does—that's just what I thought.