In his Sacramento days, he was pretty dominant.
A week ago, I saw a clip of his Sacramento highlights on Facebook, and even I was shocked at how good he was back then. I knew he was one of the best bigs in the league for a good stretch, but I never really watched the Kings or Pelicans during his peak and prime with those teams in particular.
I think what separates them is the play style but also the wins and losses. Jokic's dominance leads to wins, whereas a lot of Cousins's dominance amounted to losses, although not his fault because he never had as good of a team as Joker.
For a lot of fans, when you're winning, it's more impressive, but when you're losing, it's just meh. If Jokic was dominant but losing at the same rate as Cousins was during his peak and prime years in Sacramento and New Orleans, nobody would care.
That's why fans don't give Cousins any credit because his moments of dominance didn't amount to anything significant outside of highlight reels.