I'm not even convinced that this works well for users who want to run that work on their machines. Distributed cluster of random untrusted hardware has got to be so much less efficient than a purpose-designed datacenter cluster, and harder to manage. I get that any "free" compute is cheaper than paid compute, but at some point the gap is so wide that the coordination alone doesn't make sense.

Wasn't there some famous home-computing project that recently stopped because of that? I thought it was Folding@home but that seems to still be going.