Is it not customary for the admin to tell you what you've done to receive a ban ?.
I've had a couple of 'holidays' on single track world. Their process is first its a week, after that its a month, and after that they enforce a permanent ban. Usually for shouty matches with other members, where threats have been issued or strong sweary words uttered.
But its a series of warnings first before any holiday takes place. I think its very off for any forum to issue a permanent ban without first giving you say a week or so.
And a lot of the time other members step in and sort of 'self police' mods are only there if things get too heated, but even then they can let an argument run in the hope it will blow itself out. Things are too bad mods can issue a warning to any parties then delete offending posts.