Decred solves this. In hybrid PoW/PoS, coin holders vote with their equity. Skin in the game provides the greatest incentive for proper decision making. Decred was started by Bitcoin developers early on when they saw that Bitcoin had a problem with governance and decision making. Bitcoin's consensus rules are set in stone. Decred has a measurable and defined process for consensus rule upgrades.
StakeShuffle on Decred uses high volume coinjoins with a huge participation level due to integration with Decred's staking system. It can be used in the Decrediton desktop app gui. Nearly half of all the DCR in circulation now are using this mixing. https://dcrdata.decred.org/charts?chart=coin-supply&visibili...
It is also easy for BTC owners to trustlessly exchange to and from DCR using the dcrdex with atomic swaps. This makes the combination of StakeShuffle and dcrdex the best pathway for maintaining privacy of BTC that exists, and in a decentralized way with no custodians. https://github.com/decred/dcrdex
"Clearly, this expenditure pattern is a massive misallocation of resources. The last 20% of network hashpower provides vastly less value to the ecosystem than those same resources would if they had gone into research and core protocol development. So why not just.... cut the PoW budget by 20% and redirect the funds to those other things instead?"
"even though we could easily identify some valuable public goods to redirect some funding to as a one-off, making a regular institutionalized pattern of such decisions carries risks of political chaos and capture that are in the long run not worth it."
He gets the premise entirely wrong here. The chaos in these blockchain protocols is due to there not being a clear and well defined process for doing consensus rule upgrades. PoW miners control these chains. The power over the chain by PoW miners has become centralized into increasingly smaller number of participants with their own selfish interests. No upgrade will happen without their embracing it. Overriding the miners then becomes a vague and undefined matter of 'economic consensus' which means different things to different people and is not measurable.
Decred has consensus rules for upgrading its consensus rules. The hybrid PoW/PoS system allows for the security and fair distribution provided by PoW while allowing PoS... the economic stakeholders with the the most to lose, to make the decisions about the future of the chain.
The largest downfall in PoS is how the new coins go to existing coin holders, causing the rich to get richer .. centralizing the ownership of the network. PoW miners have hard cost to pay in the competitive market and the profit margins tend towards zero. This real cost means that miners have to sell coins if they need to recover production costs. The selling creates downward pressure until the market settles at a natural price floor. Gold buyers have understood the market price floor in relation to production costs for a long time. This lack of production costs with pure PoS systems leads to centralized ownership and a manipulated market, and this is why we see pure PoS coins with manipulated sky high market caps. I will never buy a pure PoS coin because a manipulated price doesn't satisfy legitimacy by fairness.