I think that was because all the hype we heard about Doncic emphasized the wrong aspects of his game. He was alleged going to be Magic, or Steve Nash in a bigger body, an unselfish, superior ball handler who would elevate the game of everyone who played with him.
Where, in fact, that has turned out to be a lot of baloney. He does have good handles and above average passing skills for a player his size. But his supposedly masterful skills at quarterbacking a team were far overstated, and he doesn't even particularly have the physique or stamina to fit that fast break/open court style of offense if he was on a team that tried to run such a thing. I spotted that from the get go with him, and that in particular was why I thought his play would fall short of what the hype was projecting.
On the other hand, what I (and in my opinion, the media hype) missed was that he genuinely had a scorer's mentality and skills. That, paired with his also unexpected strong rebounding, has made him a very effective half court force that I don't know many people recognized he would be.
So he has certainly emerged as a "superstar" stat stuffer. Whether he accomplishes anything beyond that, I'm not sure. It seems he has gotten quite a big head with his early success, and there is room for doubt as to how much of a "team first" guy he will ever be.