The popularity of a programming language is influenced by multiple factors. 
Recency is one very important factor, as it takes a lot of time until 
a significant part of all programmers has tried a language and worked with it enough to be able to judge it's strengths and suitability for their 
applications.
This combines with the fact, that i.e. the portfolio of libraries available for a language affect this decision significantly, so initially a lot 
more people will stick with an already established language which they already know and which has the libraries they need for their goal.

Adoption of new programming languages is therefore not simply a function of a languages features but probably follows an S-curve shape,
where initially for a language with many desirable features, adoption remains low except among a small group of enthusiasts. 
After some time a tipping point is reached, where many libraries have been written over time and distributed social knowledge about the languages strengths
and favorable applications has spread far enough for people to regularly use it for a multitude of problems. 
Then the language settles into a niche, as most programming languages have certain fields in which they excell.
An indicative example of the current position of Rust on this curve is recent adoption of a few modules into the linux kernel which were written in Rust.
spam fails_task lang_mismatch pii not_appropriate hate_speech sexual_content quality toxicity humor helpfulness creativity violence