My hypothesis is: Rust is already good enough, and ready to grow beyond status of a new/experimental language.
If you only look at Rust through its issue tracker, there are obviously sooo many things that are still missing, need to be fixed or improved. There are a few major features I'd still like to see added.
But if you look back at what has been shipped: it's a pretty good language! It already has way more features than C. It many areas it's already much more polished and mature than other languages.
So if Rust-the-language is ready to be used, let's have a closer look what is stopping people from actually using it, and fix the blockers.
I don't know exactly what is putting brakes on Rust's growth. Part of the work would be figuring this out and verifying assumptions (which Rust team has been doing already to some degree).
Is it documentation? For example, Rust has messed up SEO. Google is confused by older versions of std docs, early book versions, and stub-redirect pages left behind some book versions. This may create an offputting experience for new users if half of documentation they Google is incomplete or doesn't work. This is going to get worse with
awaitnow that all existing futures v0.1 docs/tutorials/crates were obsoleted.
Is it distribution and packaging? e.g. in my case
curl | shis a blocker, since it works very poorly with tools that automte server deployments. Regardless of whether it's actually secure in Rust's case, the
curl | shpattern has an awful reputation of being an amateurish hack, so it's hard to recommend in "enterprise" environments.
Is it lack of MSRV support in Cargo? If someone installs Rust through a Linux distro, they're likely to run into a ton of compilation errors they don't understand, because most of crates-io crates don't support Rust 1.25 any more. This may enforce users' belief that 3rd party crates are fragile, and since Rust relies on them so much, Rust as a whole may look fragile.
There may be lots of other reasons, which may even be non-technical, e.g. chicken-egg problem of lack of Rust jobs, because few companies are hiring, because there are few professional developers to hire. Maybe this could be helped with training programs, or focusing on use of Rust alongside other languages, etc.
People who use Rust already tend to really like it, and Rust itself attracts a lot of attention/hype, so I suspect it has a lot of potential to grow its userbase.