QUOTE(everyking @ Fri 25th September 2009, 3:24pm)
It seems to me the purpose of bans is to prevent people to harming the encyclopedia.
I'm sorry but that's an untenable claim. Bans are given to people for all sorts of reasons - even ostensible 'prevent harm' reasons often have a hidden agenda, related to people for whom 'the project' is NOT their priority, but their own positions in the 'community' itself, their own POV warring etc.
I'm of the understanding that there are many people here on WR who were 'banned' when 'harming the project' was not their intent, and for which the 'banning' itself has served to bring Wikipedia into disrepute (that is, WP's reputation has been placed at risk by the banning of someone). I'm one of them, and I got banned by Jimbo himself, at the behest of Guy Chapman and some others. Logical assessment of the 'harm' to the 'project' was not part of their thought processes on that occasion, and that appears a common problem over there.
For every person who has been 'banned' unfairly, even among those of us who couldn't give a fig about being banned (like myself), the processes of Wikipedia come under scrutiny, and are found to be suspect by many: a common theme in Wikipedia Review discussions, for example.