Just because someone Mains a champion doesn't mean they're biased

In fact, I feel like it gives them more insight on how truly strong the champion is or how weak they are. Obviously there's that one guy that goes "NO X CHAMPION BLAH BLAH BLAH, etc."

It really annoys me when I see a post about X champion and they make really good points about their weakness's strengths. And makes a well thought out post/video explaining. But then that one person in the comment section "You main them, so your biased, there fore your opinion is biased/wrong"

Like do they even read or listen to the points? Or just search for ways to circle jerk?