Kinda agree. Definitely puts an asterisk, like, Shamrock - that dude who used to be awesome a lifetime ago.
He was right up there, along with Royce Gracie, to show the importance/dominance of submission grappling. When the UFC first started and it was literally "style vs. style", a ton of fighters underappreciated or flat-out weren't aware of the ground game. Shamrock's strong submissions and takedowns changed a lot of peoples' perspectives.
Fighting aside, his Lion's Den pretty much ran shit back then. It produced a ton of title holders. It was basically the "Greg Jackson's Camp" of the early UFC days, and that's thanks in large part to Shamrock's coaching (which was super-edited in his TUF season).
Not trying to bust your balls, man (and really I'm not trying to come off as a Shamrock superfan, ha.) Just saying, the guy's a legit legend in the sport. It's not like he's just another Teila Tuli one-shot wonder.