The point is if you see a captcha you can actively decide not to use it. If the website has no such box then you can't decide not to use the captcha
That's not a sinister "land grab" by Google, that's a fundamental aspect of the web, predating the advent of JavaScript. You reveal your identity quite thoroughly to the individual hosting services.
And it's difficult to imagine legislating that away, as it's sort of fundamental to all network computing.
You're not going to get through a site with a properly implemented captcha just by blocking it.