Well, I haven’t been, but Steven de Guzman has. Three times:
- Has Steven de Guzman written anywhere about his third ban from Quora? (relayed by third party)
- Incorrectly banned on @Quora for allegedly having sock puppet accounts (by Steven on Medium)
- Incorrectly banned on @Quora for allegedly having sock puppet accounts (Part 2) (by Steven on Medium)
Btw: people do get unbanned. In fact, one writer got banned, unbanned, and made Top Writer, all in the past two months.