I think it is a lack of know-how. Most businesses/managements are not capable of making the decision to go for an ecosystem like Elixir, because they either don

I think it is a lack of know-how. Most businesses/managements are not capable of making the decision to go for an ecosystem like Elixir, because they either don't even know it exists (that is also true for many devs) or they do not dare to do anything non-conventional or non-mainstream, or they have the wrong impression, that the "programming language does not matter". (Well, it does! Since it connects you to an ecosystem that comes with it and its language design choices influence how easily you can do things ...) So then Python comes along and you find loads of devs for that. Once Python is entrenched, businesses have a hard time telling their devs to actually learn something new. And few devs will already explore things like Elixir on their own in their free time. And so they continue to hire Python devs. (One could also replace "Python" with "Java" or "NodeJS" or similar, the principles remain the same.)