"Most jazz drummers are better than metal drummers though, because they have the chops to play a blast beat if they really wanted to, but they dont. Plus they can do more different timed stuff and more rythym based stuff."
The better drummers are those that have experience in both. A jazz background for odd rhythms and time changes, and a metal background for speed and stamina. And even though double-bass is simple in concept, it's difficult to execute with precision and stamina.
Death's Human and Gorguts Obscura are excellent examples of drummers who have experiece in both and apply it to metal albums.