You forget the part where they mentioned a different business model that allows to dump the ad-driven one, aligning the interest of the user and the vendor. In other words, a model in which the company gets the money from the user so that it can build a product for them, rather than getting money from others (advertisers, etc.) so that the user is someone who simply has to be milked for data or sold shit. This frame, in my opinion, changes quite significantly the otherwise dystopian nature of such (future) vision. The objectives in fact are very important in this discussion. Facebook, twitter etc. need people to spend time on their platform to give value to their customers (the advertisers). Creating bubbles, fomenting incendiary content, etc. are all functional to that objective. If the business model was different, the same might not happen.
In any case, the current features that exist (and that are not the speculations on the future in the manifesto) allow the users to customize the rankings as they want, without AI or kagi doing it for us. If I don't want to see fox news when I search for something, I make the conscious choice and downrank it. If I want to see guardian and apnews, I uprank them. The current features empower users to curate their own results, which is very different from an opaque, black-box product doing it for us for specific reasons like might be the case of Facebook.
Ultimately, someone will make a decision about how to rank results in a page. Some algorithm needs to be used. What's a better alternative, compared to me providing strong inputs to such algorithm, that does not raise red flags?