Why do people still believe in the Holocaust?

Can someone please explain to me why everyone's expected to agree with the official story about 6 million Jews being killed under the Third Reich?  I mean, in many countries, it's criminal to even *question* the idea that something might be wrong with that claim.  And you basically get blacklisted everywhere for doubting it, being labled as a denier.

I've done some research on this, and there's actually a pretty solid case that there was no so-called "Holocaust".  One that I agree with, in fact.  Here's an example of an excellent debunking:

http://www.ihr.org/books/rassinier/debunking.shtml

So, with a case that solid, why is it such a big deal?  Why do people believe that there was a Holocaust?

Imagine the US Government making it illegal to say "9/11 was an inside job."  People would shout even harder that the claims are true.  Removing a youtube video gets more people to post the same video.  Restricting the rights of gays or blacks creates more effort against those restrictions.  Resistance creates opposite resistance.