I've always been deeply skeptical about the top/bottom split. Or the butch/femme split for that matter.
It's a construct people use to help them compartmentalize better. It has very little bearing on reality, and is pretty toxic, to be quite honest. Labels very rarely help when talking about human beings; they usually only divide and hurt.
I personally really hate these butch/fem, top/bottom splitting. I mean fictional characters who are clearly a bot or a top is still hot af, but saying two bot can't have sex is extreme.
I have seen a lot of people around me saying something like the top has to make money to feed the family and the bot must have cooking skill, or the top should not be crying, the bot should not drive, etc. I mean what? Straight men and women see gender roles as a bad thing and trying to get rid of that, and here you're trying to mimic that bad thing?