The same kind of companies that were all hyped up on Ruby on Rails, and then moved to Java when performance mattered.

Hype driven development is a thing.

Given a large enough sample size, there will always be companies which ditched technology X for Y.

Unless technology X is irrelevantant.

You'd be surprised at the extent hype influences decision making when it comes to choosing which language to use (even in companies you mentioned), at a significant cost down the line. I'll just say I know people at one of the companies you mentioned, and the amount of friction and cost due to them using golang is quite remarkable.

No offense but I'd rather trust the engineers of all these companies combined over an anecdote on the internet.

Not to mention technology change always generate friction. You just can't please everyone.

Assuming those engineers were making sound decisions and not pimping up the CVs at employers' expense.

Exactly what happened at the company I'm talking about.