I'm guessing this post was down voted because of author not content because I can't find anything wrong with the latter.

But the fact that he got his degree with a boring trivial paper, when he had several of his greatest papers in hand, suggests that there was no fixing them.

Yes this is evidence towards him not being sure those papers could be fixed.

Getting a group of people to function together so that their output is smarter than any one of them is hard, a deep and unsolved problem.

Exactly, coordination is hard. Perverse incentives, Goodhart's law, agency dilemma, etc.

The normal outcome is that their output is dumber than any one of them.

See most non-profit organizations ever.

The scientific community solved this problem from the late seventeenth century to late nineteenth or early twentieth century. Although engineering continues to advance, and more powerful tools such as DNA readers continue to advance science, science itself seemed to run out of puff after Einstein.

Stagnation in our time.

While I think you are right for most fields, I would argue we see a relatively healthy culture and even functional institutions when it comes mathematics since they have been making considerable progresses. I'm continually shocked at just how many of say recent advancements in evolutionary biology are basically rediscoveries of what Darwin himself said! In general reading and taking seriously the best of old thinkers is an excellent use of spare time for the intellectually curious.

Peter Thiel makes the case that outside of computers we aren't seeing much advancement in engineering either since at least the 1970s. He cites cultural reasons but also notes we've effectively outlawed innovation in the world of "stuff" but not the world of "bits", so those who like innovation go to Wall Street or Silicon Valley. Arguably the net impact of more people going to Wall Street to practice financial voodoo have been decidedly negative. If it was worth paying the opportunity costs for all those people to go to Sillicon Valley also may not be as clear cut as we may like to imagine, especially if you take Eliezer's arguments about the dangers of AI seriously and remember that the area of "stuff" includes such fields such as energy and medicine which radically alter quality of life.

Not only do many confuse progress of technology for scientific progress, they are used to thinking about building up knowledge about the world and healthy institutions of science as being basically the same thing. Which isn't true at all. We've had millennia of gains in naturalistic knowledge before we ever came up with the scientific method let alone the culture of science! Westerners from about 1700-1950 did something remarkably right to do so much with so little. What could they have done with the tools available today! I hope no one will bring up a low hanging fruit counterargument here, as it is hard to argue that what they picked hadn't been low hanging fruit for a respectable and advanced civilizations like that of the Chinese as well.