I'm sorry but this is just false.
There were tons of people discrediting Kobe and claiming he was overrated or not a GOAT contender when he was still living. He had tons of stans too but that's what polarizing means. It means that people either love you or hate you without much nuance. It doesn't mean that you're widely disliked. Obviously, Kobe had tons of fans.
This definitely applied to Kobe because the rape trial soured his image among many people and lead to sports media downplaying him and there were tons of NBA fans who felt like Shaq gave him his first 3 rings, that Duncan was a better player in the 2000's, that he was a ballhog, a Jordan copycat who couldn't compare to the real deal, that he was never the best player in any given year, etc.
I remember these discussions being very frequent in basketball when Kobe was still living. Obviously, there were people who were praising him and calling him a GOAT too but it wasn't as universal as what you're saying.
Hell, I remember there was a corny joke that was widespread online back in the 2000's talking about how, when Kobe dies, his tombstone would say "He finally passed."
Kobe pre-death was the definition of "hate him or love him." He had tons of haters in sports media and basketball forums who were discrediting him and claiming that he was barely top 10. And they'd always claim that Duncan was better.