Then what's stopping mihawk from doing the same?
Ace did it, whitebeard, luffy, big mom pirates would've on 2 occasions if they weren't wished down by outside forces, nekomamushi, and i don't fully remember tbh but that might've been law/kinemons way up
When was it ever said roger wasn't capable of going there?
We don't know why
I still hope he at the very very least fought some sort of semi relevant marine