Rails is a huge problem, but the most mature libraries/frameworks in Go/Rust are all micro-frameworks, which isn't much of a replacement. Maybe some .NET frameworks would be a better choice.
Though I'd personally do it in Elixir but again, speed. GitHub is huge and should rise up to the challenge.
I've seen good and productive Rails teams but they had to deliberately stop themselves from certain practices, otherwise they ran into problems. Long topic though, and people get very emotional and preachy defending Rails so it's a fruitless discussion 99.9% of the time.
In the end use what you feel works best for you and your team. Objective differences in programmer productivity, machine speed, iteration speed and other metrics does exist though and it's very tiring to see people constantly pretend otherwise.