Anyone who's read the discussion pages for a few Wikipedia articles knows the intense debates that can arise even without vandalism.

Look at the discussion page for tennis player Andy Murray, who recently lost to Roger Federer in the final of the U.S. Open. Murray was born in Scotland. The current discussion page has over seven thousand words of back-and-forth about whether he should be described as a British or a Scottish tennis player. (I copied the talk page into Word, deleted anything not directly about Scottish/British, then had Word do the count.)

Those 7,000 words go all the way back to Wednesday of last week. In addition, there are four archives of the talk page The actual article about Murray has some 4,200 words (ignoring the tables of statistics and the text inside footnotes).

For the sake of argument, let's assume none of the contributors were Scottish-independence zealots or those who oppose them -- just folks with strongly held but differing ideas. An awful lot of energy, some of it bound to discourage others from joining the discussion.

So that's part of the why of any ban, I think. I know nothing about the details of the individual who got banned -- but it's always easier to mess with things than to clean up afterward. The notion that the community will self-police has some merit, but a determined, energetic person (to say nothing of one who's also self-righteous) can find endless ways around that.