This has nothing to do with being a hater. It's just a simple fact that a player who was a net negative for his team in a lesser league isn't suddenly going to become a star in the best league in the world. Which, given the draft capital the Hornets spent to acquire him, is what his peak needs to be to not be a bust.
It makes sense to draft tall players based on potential. There aren't that many tall people in the world in general, much less those that like sports enough to put that height to use in basketball. But LaMelo wasn't tall enough to justify taking him on potential. Giannis and Porzingis are the types of players you draft on potential. "Shorter" players have to be drafted on talent, and LaMelo's only talent right now is putting up empty stats so that he looks good on the surface, whilst in reality having horrible plus/minus and not leading his team to wins.
What he did in the NBL is exactly what he's doing in the NBA now. And I still have my doubts regarding how LaMelo will hold up over a full NBA season, because this is the guy who bailed out of a much shorter and less taxing campaign over a sore foot. Obviously he has the potential to improve and become a solid player, everyone who is only 19 does. I just don't think he has the same potential a 7-foot player would to suddenly have a breakout season.
As for Ucan's comments about Europe... I notice that a lot of Euro teams play very deep rotations, making it relatively hard for any one player to stand out as a can't miss prospect, or in the case of older players, someone who should be in the NBA. The scouts therefore have to watch game footage and ultimately make a gut call. To use Doncic as an example;
Doncic 17'-18' (All competitions): 74 GP, 25.1 MPG, 44.9% FG, 30.9% 3PT, 78.8% FT, 14.1 PTS, 5.3 REB, 4.5 AST.
Real Madrid went 64-19 overall and won the Liga ACB + Euroleague.
Doncic was clearly NBA ready and skilled beyond his years, but people expect higher numbers from a 'superstar', and don't expect their team to use them as a sixth man so often (Doncic only started 40 games that season).