i'm guilty of this, but it really depends (in my case) as for which trope i'm talking about. Many time you really just want to talk about the proagonist, and saying "the uke is really op" may come as weird, whereas "the mc is really op" fits it better, or when characters are versatile.
If the sentence fits better to describe exactly the "uke" or "seme" personality, i much rather prefer using "top" and "bottom", for pretty much personal preference. I guess it all depends on context !
It's not only for BL. In Isekai stories also, although there majority are written from Female side only. I also miss ML FL era. ( ･﹏･)Now MC and ML is used there too. I get so confused. I check review before reading a story. These days I don't get any context as How would I know who the MC is even.
I don't know if it's just me, but uke/seme sound too 2000 or less, with the quite particular yaois that go with it
in terms of bl, i thought the purpose of mc/ml was to eliminate the need to address the characters by their positions (top.bottom/seme.uke) but imo since it has become so common that the story is in the bottom's perspective anyway, mc is just sorta synonymous with being the bottom now. i notice a lot of people refer to the mc when addressing the character that bottoms. so all in all, ig it's starting to go back to addressing characters by their positioning, just packaged in a different box lol.
because as you mentioned, not all stories are written in the bottom's perspective, so in this case, the top would be the mc, right?, but im sure the majority will automatically assume it is the bottom.
I personally just use top/bottom if it's smut related and describe their features or their names, when it comes to fluff stuff and no position is clear. When it comes to BL, this mc/ml stuff feels like an attempt to cover up the obvious ╮(￣▽￣)╭
MC/ML sentences are hurting my brain. Not every story is written from Uke's side. Why would you even set the two party like that?