[pcwalton]

In my opinion, it's because the Go team put a ton of effort into getting M:N working and didn't rigorously evaluate any other alternatives in Go, once moving GC was implemented.

I'm not convinced that 1:1 wouldn't have been a perfectly reasonable implementation strategy for Go.

[weberc2]

This is surprising. It seems like Go gets pretty high praise from all over for its threading model, and it seems like there are relatively few high-performance servers that are built with 1:1. Am I wrong about that? If not, what explains this?