I’ve never really thought about it but I would assume it’s cause MC and ML are pretty close abbreviations and could be easily mixed up unlike FL/ML. Also with most queer stories I read/ remember it goes between the two leads as the MC whether they are top or bottom pretty evenly. While the few hereto stories I’ve read the mc is mostly always the FL. So it helps classify, maybe? At least that’s how I think of it ヾ(❀╹◡╹)ノ~
Well for me, I read soooooo many stories and novels that it’s genuinely hard for me to remember names. Sometimes stories, such as 2HA, don’t have an ML or MC so saying top and bottom is easier, for me especially when it comes with stories I binged in a day. Also, for hetero stories, it’s easy to differentiate between “the girl” and “the guy.” I don’t read many GLs, but normally I think those are differentiated by hair color or whatever.
For me, I call them mc/ml and it's also because I'm sht at remembering names. Pretty much goes to any genre of manhwa I read be it hetero/BL/action. I tend to remember the really popular mainstream ones though like Kim Dan and Jaekyung (I don't read Jinx but I always see it being discussed in comments and tiktok)
Is it because you guys read too much that you always call the characters as "top" or "bottom" or is it because you are sh*t at remembering names? I find it disturbing but I'm also curious.