But why market it as "gearbox is a web framework for building micro services written in Go".

If it's not production-ready, who are these micro services for?

It just seems not even close to polished enough to share it with the wider community. Someone may take this at face-value and try and use it for their own purposes, only to discover it's a purely academic pursuit with no actual merits other than 'oh we might be able to spuriously improve performance.'

I think other commenters have got it right in saying that processing requests is _not_ the bottleneck of most micro services, but interaction with a storage layer or network speed.