I agree that advertising as a business model incentivizes bad things, but as for censorship the only things I'm aware of advertisers aggressively rejecting are

I agree that advertising as a business model incentivizes bad things, but as for censorship the only things I'm aware of advertisers aggressively rejecting are things like Naziism and its relatives. This is because advertisers don't want to alienate vast populations of people. They don't want stuff like "blacks and women are intellectually inferior, brought to you by Coca Cola!" I see mainstream ads in "fringe" content of a variety of types, so they don't seem to care much about things being off-beat or strange. They don't seem to care about indirectly sponsoring UFO videos or fringe views of history that aren't transparent efforts to dehumanize people.