What I mean is that if you are consuming news media and seeing only one point of view, something is wrong. I feel like I frequently see commenters who implicitly believe there's only one valid side to an issue, and the other side is just racism / bigotry / corruption.
True, that's a call for diversity. But if you're seeing multiple perspectives butting heads consistently across the news media consumed by an entire country, that's divisive, as a result of having diverse perspectives and coverage. To your point, though, that's likely more the result of a lack of diversity at individual sources and people picking and choosing to consume less diverse news. "Divisive" isn't the right word.
Do you mean "media is supposed to be diverse"? Because that's a goal which is commonly held to be good.
I've literally never heard anyone say "Media is supposed to be divisive", nor heard the case for it. I'm going to assume that was a typo?
For the record:
Diverse: showing a great deal of variety; very different.
Diversive: tending to cause disagreement or hostility between people.