That proves that Tool is a progressive metal band.
All post-'Power Metal' Pantera = Thrash metal. Sometimes they're labelled as "Groove Metal", which also makes sense.
It is a metal subgenre. Whether or not you like it, it is. Why do you think it's called "Nu-metal"? The vocals are sometimes influenced by hip-hop/rap, that's about it.
You failed to mention anything about Alternative Metal.