For twitter at least, that would have to be done manually. It still shows a timeline for grey checkmark (government) accounts, and a "best of" type page for all other accounts.

Most sites serve a special version of the page to visitors with "googlebot" in their UA string and/or coming from an IP range google controls with more SEO'd contents too.

That would be equivalent to demonetizing the entire web. Free content would win out over paid content regardless of quality. As the old adage goes, "when you're getting something for free, you're the product being sold." Only sites making money by, shall we say, "indirect" means would be able to survive. A search engine which prioritizes free content over paid would become nothing but a propaganda engine.

Because Google wants the web to be broken like that, they're also part of the design team of tech behemoths that made the internet shitty und no fun.

They have had ways of letting people who give Googlebot access to content that requires login for a long time. A decade?

Because people can get a login. If the best quality result is behind a login and a paywall, I still want it to be the first result. Only quality should decide ranking.