Because players sometimes win MVP in years that aren't their best. Usually from the "best player on the best team" philosophy.
Oh no doubt. But Kobe's MVP season isn't a suitable comparison for Zeke during those aforementioned seasons (which the OP specified). Kobe was still arguably the best player in the league (Zeke wasn't), he was second in scoring with 28 ppg (Zeke averaged 18 ppg in '89 and '90 - second in scoring on his own team in '89), named in the All-NBA first team (Zeke wasn't named in the 1st, 2nd or 3rd All-NBA team during both those seasons), he was by far the most impactful player on his team (whereas the Pistons were extremely balanced, and while Zeke may have been the best player, the small margin couldn't make up anywhere near close to the difference that Magic had on him - Lakers had a better team record in '89 and comparable record in '90 - along with Magic having far superior stats).
I mean I don't know why someone would be confused as to why Zeke didn't get a MVP during '89 or '90.
