Cracking joints does not give you arthritis.. Why not?

I read that the most widely accepted theory of why joints makes the cracking/popping sound, is because of cavitation. But the article also mentions that there is no basis for saying that cracking joints gives you arthritis. From reading about cavitation, i know that it can cause severe problems in pumps, turbines and propellers. The cavitation actually "punches holes" in the metal. Have a look at the wikipedia article.

And the question is then: How come it is not really bad for you? If cavitation is powerful enough to do those things to metal, why doesn't it do it to your bones? Is it just that the "amount of cavitation" experienced by propellers etc. is much larger, or is it that the cavitation jet does not hit the bones, or what?