Folding at home does not use a blockchain, further proving non-grifters don’t need it. That was the point being discussed, not distributed computing as a concept.
I don't think you are being fair to the previous poster. As I read it they are simply pointing out that there is precedent for such decentralized contribution of compute resources. However folding at home doesn't allow to reward users for their contributions AFAIK. So maybe if a Blockchain based reward system could be layered on top of that it could increase participation. That's a big if I grant you but don't see how it is completely inconceivable that such a thing might be possible.
I think the word blockchain confuses people, including you and the previous poster. Maybe you could clarify your “layering” idea and how it would work for further discussion.
Folding at home can track user contributions and issue micro/payments as they see fit. Crucially, this does not need an immutable chain of truth to do.
Instead, if we added a blockchain, then we would require 2 sets of participants - those who run the useful simulations for science, and those who run the useless calculations for the blockchain. A complete waste of resources.
No idea about the previous poster but I'm pretty sure I know how blockchain(s) work thanks. I don't claim to have a concrete proposal but the idea of proof of useful work has been around for a while as a research area (https://eprint.iacr.org/2017/203.pdf). Having a system that supports arbitrary computations might be hard, but perhaps any task for which solutions are easy-to-verify but difficult to compute might be a good fit. Alternatively, if creating an open/decentralized compute system is a goal then a proof of stake blockchain could allow users to post tasks with associated rewards (again in cases where solutions are easy-to-verify but hard to compute).
I imagined if it was proof-of-work the mining would actually be the compute work requested. Everyone is racing to solve the problem just like in Bitcoin, except the problem is the requested GPU task. The fastest/first one to provide a result gets to update the ledger (and receives the reward).
Maybe you run a private platform too like git/GitHub if there are real world payments and user accounts, but I wonder why couldn't that technology be used? Does "blockchain" just have an irreparably bad name at this point?