I saw a clearly oblivious poster, who's been commenting quite regularly who has been [dead] since 2013. I couldn't see anything controversial in his history.
I'd love to see who you're taking about. I keep showdead on and sometimes look at the comments history of dead comments. I don't think I've ever seen a profile that left me guessing as to why they were banned.
I’ll volunteer myself as an example, as I was recently shadow banned (or some variant of banned). My other comment in this discussion has some details. I don’t think I am particularly controversial but maybe you can share a different perspective.