> We start by finding someone whose judgement we trust and subscribing to their feed, and then we find out who they trust and subscribe to their feed, and so on.

I do this, but then to avoid echo chambers I do occasional fault injection where I pick someone that one of my feed is at an opposite pole to in some salient, on some axis, and inject them to my feed for a while. Maybe I have something to learn from them, maybe I don’t, maybe they stay on the feed or maybe they are removed. I hope this helps me avoid groupthink.

I do the same. Case in point: I started to follow someone's blog because of their technical achievements, then I realized I don't like their political views _at all_, but I keep them on the list mostly to keep myself on my toes.