I mean, maybe? But wouldn't this be self inflicted anyway? As far as "earlier" goes, Pulver made his debut at UFC 22 as a lightweight, in his fifth professional fight, in the same year he debuted. So, there's really no conceivable window there to give him any bonus points there.
He left the UFC on his own terms, as the champion, only to get blasted away by Gomi, Mach, and Bang. Which I think answers a lot of questions about where he truly ranked during this time frame.
If anything, you should be asking this question about Sherk. Pulver's decision to leave as the champion was, in part, directly responsible for UFC abolishing the division, along with the Penn-Uno draw.
Who would Pulver have even been fighting had he stayed with the UFC? As far as I remember, he had already fought the top fighters in the organization. I guess avenging the Din Thomas loss would have been good for his legacy, but not nearly as good as if he had managed to win those fights against Gomi, Mach, and Bang.
I think he actually made the right decision in terms of leaving and going to seek out fights with the top fighters in which he had never competed against. If he won those fights, he would be considered an all time great lightweight.