Imagine reading someone else’s mind, only to discover that they are reading yours... Mind-stack overflow?

for certain classes of problems, sure. But how about “embarrassingly parallel” jobs (e.g. weeding a garden) or even “idempotent OLTP” jobs (e.g. studying several subjects at once)?

(Technically these aren’t best expressed as SHM but rather as a tuplespace or greedy worker-pool abstraction, but they can be achieved starting off with “just” an SHM threading primitive, so they count, I think.)