Its a great question-- our developers had never used it before and found it counterintuitive and hard to find good information on how to use. Projects are under time pressure so it's hard sometimes to have the mental space to properly grok a new framework, especially if its quite different.

I'm sure it works well for Google.

Also the support tools are lacking generally compared to say JSON or SQL or Python or any other technology.

Bugs were hard to diagnose-- I'm assuming if you were a grpc pro this would be ok.