There's an argument to be had that they would not have been successful enough to need to scale without the speed of development provided by Ruby.

Yep, also a lot just migrated some components to more suitable languages but the for the most part remained Ruby.

You can scale anything if architected right.

You can't make languages fast and fun to write in if they aren't that to begin with. There's a lot to be said for dev morale and productivity.

Which? Apart from the twitter case, which was ages ago and largely overblown, there's no case that I can remember of ditching ruby for tech X because "for scale". There are lots of examples of companies using other tech rather than ruby, but usually for different reasons (python ML tooling, go for some performance bottleneck, Java for hiring).

Twitch, LinkedIn, Soundcloud, Grab, Parse, and Deliveroo. GitHub and Stripe are both transitioning off.

I.e https://news.ycombinator.com/item?id=20349004

"I worked at Twitch from 2014 to 2018... No more Ruby on Rails because no good way was found to scale it organizationally; almost everything is now Go"