"Pass it over to some other thread"

What you are suggesting here is exactly what Erlang provides for you. Each connection is a light-weight process inside the VM. The VM then schedules these Erlang processes against native threads. The difference is Erlang has perfected and proven that it can do this reliably over 20 years of development. You would be implementing this by hand, and guaranteed to screw up because its a very hard problem and you are not the smartest person in the world.

Hybrid solutions with Evented I/O and Multi-threading end up being the solution, Erlang is a hybrid out of the box.