To the statement “By the way, if as an advertiser, you do want any of that stuff, you still have the option to target specific videos/channels. That’s always been true. YouTube is not, as far as I can tell, removing the ability of advertisers to pay for ads on mostly whatever they want.”
I had a $100+/mo Adwords campaign set up to promote a video of mine, a fairly crass but otherwise tame song with lyrics in the description and a static picture, and they terminated my ad campaign, saying that “we don’t allow the promotion of content that’s likely to shock or disgust.”
But ads are still running on my video. So basically the opposite of what you described above happened. I’m still being paid for my content, but they literally will not take my money so I can get higher views. I find that quite odd myself.