Basically for going against Facebooks policies.

Here is a news story about it

From reading the above link you would get the impression that Facebook have a chain of people reading all the posts that go on Facebook. Considering the millions of post they get posted every day, that would be impossible.Facebook use ther computer programs, what some people call algorithms, to check for certain words of phrases that may indicate posters are violating Facebooks rules. And just like the speech recognition Im using to write this, these computer programs get things wrong. So some people are banned when they shouldn't be. Apparently there is a way to requested a determination on a ban. But at the time of writing this, the link to the form you have to fill in to request a determination is not working.

However regardless of their determination, if you check out Facebooks policies ,that you agreed to, by using Facebook, you have no right to continue to use Facebook,if they don't want you to use it.

If you don't want to be banned from Facebook and don't want to abide by their rules, a work around is to write whatever you want somewhere else and link to it. That's what I do, but not for that reason.

See. Why I prefer not to directly write on Facebook and

Facebooks real Mission