Do these singers have a good technique ?

Hello everybody, I'm sort of new here, so I was wondering, whether these guys have a good technique or they don't, thanks!
1.Chris Cornell
http://www.youtube.com/watch?v=XmIqIVxUuKs

2.Marco Hietala
http://www.youtube.com/watch?v=9_vSgZU3FaQ

3.Chester Bennington
http://www.youtube.com/watch?v=Gd9OhYroLN0

So these guys are my Idols, ofcourse I would include Mr. Ken Tamplin. But I think everybody knows that he's technique is not even questionable, haha.
Rock on!
Comments
The heavy distortions on Chris Cornell and Chester Bennington may cause their singing careers to be cut short. These are extreme distortion and do not sound safe to me.
Their cleaner sounds are more sustainable, and sound pretty good. Marco Hietala sounds for the most part, like decent technique.
All three are great singers. Hopefully they will avoid vocal damage from too much glottal shock.
Bob
@FML,
It is sad that some of the sounds that have made an artist famous are the very techniques that eventually destroy their careers.
We can duplicate or approximate these same sounds by using safer methods and by careful application of these methods. It only takes a little distortion to go a long ways. It's not an "all or nothing" thing.
There is a lot of art and craftsmanship to singing that many do not realize.
Bob
I understand what distortion means now.