[Lerc]

Well preemption and blocking should go hand in hand. The distinction of whether or not that's multi-threading is more of a semantic argument. I'd consider them the Amino acids that the multi-threading protein is made of.

The entirely async model means that if something accidentally endless loops, it kills everything. The only reason why we get the "This script is taking a long time" is because some preemption is provided as some magic beyond the scope of the JavaScript itself.