At the same time, there is a sweet spot in popularity, when there is a very good quality/noise ratio in the library ecosystem, I'm not sure though, if rust's there at the moment.
A reliable recipe for 0 dependency Rust binaries so long as I stayed in the Rust ecosystem would be a good motivator to use it.
Also to answer your comment directly. Being mainstream != lots of help, resources, answers, samples, high quality/well maintained libraries. Being mainstream means that a lot of people have heard about you and a lot of people try using you / pick you up. Sometimes mainstream things do get to that place, sometimes you find yourself in an immense "the emperor has no clothes" ecosystem where everyone wants to use X because it's the cool/hot new thing. If you don't understand what the tool you want to use is good for and you forge ahead, most of the times, you will have a bad time.
Actually, if there's anything that someone fresh out of school learns in the industry, is that you do use things that are mainstream and really popular (in the particular niche you're targeting), because that's what your colleagues and management expect.
OTOH, when people come and say, "we'll rewrite this in X - it's the hot new thing, and it can do it all so much better, so don't worry about IDE support etc!", and push it through, the usual consequence 3-5 years later is a bit-rotting codebase that is hard to work on and maintain, because the people who pitched it have moved on, the tooling was never great and now doesn't even see bug fixes, and new developers on the team have to undergo a long initial ramp-up process to be able to do anything.
Sometimes it works out, sure. Usually when the hot new thing becomes mainstream eventually. But most of them don't, so unless you like to gamble, the safest bet is to wait and see and then adopt it. Let someone else be the guinea pig. The more immediate productivity gain is very, very rarely worth the pain.
At a previous gig, a problem dev, who insisted on only using Erlang, was painted into a corner by eng at large who did not want to learn/support another language (Ruby, Python, JS, Java, and R were all over).
This dev eventually got fired, as they didn't really contribute much to "the big picture". Since their efforts were so limited in scope, their Erlang work was quickly replaced using the other languages, and consumers of the results never noticed.
YMMV. But that's a old standard that should probably die