There's some overlap, but ads aren't the only thing using this. Google Fonts is the classic example of something that does add value (nice fonts) to a webpage, and as such isn't blocked by most adblockers (including uBO) by default, but is still able to use this for tracking because the same domain serves the font files on every website using them.
Very insightful response. The tendency is to look at the cookie problem as an advertising problem. Whereas, there are other cross-origin use cases that are not adverts but pose the same tracking threat. Anything on a CDN (like common javascript libraries) share this trait.
Thankfully we have Brave (and I think Vivaldi too). When the blocker isn't an extension, Manifest v3 doesn't matter much. Brave does CNAME uncloaking too, even though Chromium doesn't provide an extension API for it the way Firefox does.
Personally, I use uBlock Origin more to block obnoxious ads than to block the tracking.
I'm not sure I really care that much about tracking, honestly. So what if reddit knows I bought a toaster on Amazon recently? What are they going to do with that data, show me toaster ads? I'm going to be blocking that ad. Sell the fact that I bought a toaster? Whatever. It's all going to be so advertisers can personalize ads...which I will be blocking.
Wouldn't simply installing an ad/tracking blocker like uBlock Origin be just as effective, if not moreso?