The much maligned “Trusted Computing” idea requires that the party you are supposed to trust deserves to be trusted, and Google is DEFINITELY NOT worthy of being trusted, this is a naked power grab to destroy the open web for Google’s ad profits no matter the consequences, this would put heavy surveillance in Google’s hands, this would eliminate ad-blocking, this would break any and all accessibility features, this would obliterate any competing platform, this is very much opposed to what the web is.
It will stop bots/scrapers/etc dead in their tracks seems to be the main reason.