Every time I see a company post about how they’re changing programming languages, I tend to believe it actually happened because engineers with enough political clout decided they wanted everybody to change to their preferred language, not truly because of technical reasons, but because they just wanted to be paid to write in a cool language. But, of course, you’d be lambasted by your colleagues if you didn’t provide technical reasons, so you go and hunt for technical reasons that seem insurmountable and build a case for it, turning a blind eye to perhaps less exciting solutions that don’t require a programming language change.
(It’s sort of like how a cop in America can find you doing something illegal in any circumstance if they look hard enough. Except in this case, it’s a matter of finding technical deficiencies.)
This strategy highly depends on clout though, which is why I think technical arguments are frequently really a façade. If, say, a junior programmer doesn’t have clout, even presenting an equivalent technical argument won’t lead to a change in programming language, especially if it’s the senior’s favorite. I’m sorry to say, but most tech organizations aren’t meritocratic or egalitarian in this way (and perhaps they shouldn’t be).
As it pertains to the article—which again I don’t claim is all “fake” politicking (I don’t know anything about or anyone at Discord)—they mostly ripped on garbage collection. They specifically talked about how GC was bad because their LRU cache had to be scanned, which was part of why they observed spikes in their metrics. I wonder why they didn’t try doing things like putting the LRU cache into foreign, unmanaged memory to avoid garbage collecting it. Easier said than done, but why not?
I think using any language with any serious and large project will find deficiencies in the language. At some point in a product lifecycle it’s more profitable to just work with and ameliorate those deficiencies than do rewrites where the new deficiencies will be completely unknown.