From there Elixir/Erlang syntax wise, functional and process oriented, without OOP support looks like a pretty weird and unfamiliar place. It takes some time to become competent in your first programming language and when it comes time to branch out people are often not that willing to move too far away from their comfort zone - i.e. they will tend to stay pretty close to that centre of gravity. Learning something as different as SQL can be challenging enough but at least the potential for short term ROI is pretty good on that one.
I seem to recall that at least initially a significant portion of the people interested in Elixir were experienced (long time) developers who have been using mainstream languages and runtimes long enough to be more aware of their limitations and shortcomings. The appearance of Elixir just made it a little bit easier to try Erlang’s process oriented architecture and flavour of functional programming.
Aside: How did WebAssembly even get on that list - it’s a compilation target, not a programming language.