It's tracked by Google even if you never visit a page operated by Google. Non-Google websites that include Google tracking are contributing here (which is most of the web).

The sentence you cite suggests that it's "just" such sites that see your activity, while it's a third party (Google) that does as well and that is the issue here.

Sure, technically you could argue that the tracking is "part" of the website that you visit, so it's technically still "only" the site that's tracking you. But let's be honest here, no reasonable non-hair-splitting non-geek would read it that way.