I was thinking about this today. They even have a thread over at reddit about it. The admins tried to tell people they only permaban after issueing several temp bans.
No they don't. I've only ever gotten permabans. I also don't think anything I did (some angry shitposts. No threats, harassment, or anything like that) deserved a permaban. Like they could have given me a temp ban or a subreddit ban, and I would have been fine with that. They for some reason went nuclear on me and went straight to site-wide permaban. I don't know why, I filed appeals, I sent messages. I tried to reason with them. Nothing. They go nuclear as standard practice and are completely inflexible about it.
I've heard that certain well-connected people have been banned, like wall street people and politicians, but they know who to call at reddit HQ and get themselves unbanned. That's not the case for the rest of us, and I don't know about the rest of you but I can't afford a lawyer.