Yeah I know where Serj's style came from. And Decadence may have been a FNM 'rip-off' musically, but personally, I can't hear Patton's influence in Palumbo's vocals. I may be missing something though.
I'm not arguing with your point about Patton inspiring the vocal styles of many, but like I said, even if he never became big, talent is talent. I'm sure many of the artists inspired by his style would still exist today (discounting your above examples). They would almost certainly be different, but who knows, maybe if Patton never exsisted, we'd right now be talking about how many vocalists have ripped-off Serj Tankian's style.
I just think that it's slightly unfair to say that so many of todays rock vocalists would be nothing without copying another artist. There's a line between influence and complete dependence.