It's completely wrong that performance doesn't matter for the server side, in fact it's the complete opposite.
Javascript is a fine language for client-side software because the client is paying for it (and the client's computer, tablet or phone is running idle most of the time anyway)
Firms that run web services pay dearly to run their servers on the cloud, expect to run at a high utilization fraction, and if they ran their infrastructure on a slow language like Ruby they would be paying cloud bills 10x what they'd get for infrastructure written in Go.
The people who make the decision are paying the bills and that means they make a very different decision.
Javascript is a fine language for client-side software because the client is paying for it (and the client's computer, tablet or phone is running idle most of the time anyway)
Firms that run web services pay dearly to run their servers on the cloud, expect to run at a high utilization fraction, and if they ran their infrastructure on a slow language like Ruby they would be paying cloud bills 10x what they'd get for infrastructure written in Go.
The people who make the decision are paying the bills and that means they make a very different decision.