At the end of the day, the ref is always right!
Only when the ref is properly trained and appropriately certified!
Seriously though... I never got banned, but I have seen a few interventions by moderators that range from just bad-mannered to appallingly one-eyed. Yes, you may be volunteers, but if you accept the responsibility, then you should also be prepared to be completely fair and impartial at all times. Just because you (very willingly) give up your time to moderate, doesn't give any moderator the right to engage in personal vendettas, or embark on their own particular agendas. This has certainly happened in the past (although it is rare).
Overall the standard is high, but I did follow the thread that I presume MOR is on about, and I can't for the life of me understand why a ban was called for...