Not crazy, but you would be excluding 85% of the top 100k sites, including stuff like Github. I'd rather just try to block the Google domains themselves.
> I'd rather just try to block the Google domains themselves.
This works to some extent but falls short of really penalizing the site owner for installing the trackers (of course, they probably lose some revenue but that's not enough).
If sites had a rating reflecting how "tracky" they are, then, given a choice, people who care would tend to pick the less tracky one. Benevolent browsers, search engines, and other tools can enable them to make this choice.