What you’re saying is only partially correct - Yes, for more exploratory programming for a new product with full US/EU/CANZUK based dev workforce it makes sense to prioritize maintainability.
For a company complaining about infrastructure costs for a product that has been cloned many times over, and which is large enough to hire offshore devs, the cost equation favours rewriting in something like Go, Rust or even Java. These are quite tailored towards Reddit’s current use case and many companies including Twitter did that rewrite.
Using a language with a faster runtime makes the system run faster. But it does not compound. So you are limited to a ceiling at about an order of magnitude faster execution.
Making better decisions on a daily basis compounds. You evolve towards a better architecture. Which can make the code multiple orders of magnitude faster.
One of many examples: In a complex system, developers often have a blurry vision of what can be cached, in which situations it can be cached, and how cache invalidation should be done. While in a more elegant system, the borders between different approaches to caching are clearer. Leading to the more elegant system being multiple orders of magnitude faster as it can leverage the different caching layers (in memory cache, on disk cache, the CDN ...) more effectively.
This doesn't sound like argument in favor of Python, though. In my experience, Python code quickly reaches the level of an impenetrable word salad, at which point all the compounding stops.
For a company complaining about infrastructure costs for a product that has been cloned many times over, and which is large enough to hire offshore devs, the cost equation favours rewriting in something like Go, Rust or even Java. These are quite tailored towards Reddit’s current use case and many companies including Twitter did that rewrite.