Rust isn't standardized. Last time I checked, everyone who uses it depends on its nightly build. Their toolchain is enormous and isn't vendorable. The binaries it builds are quite large. Programs take a very long time to compile. You need to depend on web servers to do your development and use lots of third party libraries maintained by people you've never heard of, because Rust adopted NodeJS' quadratic dependency model. Choosing Rust will greatly limit your audience if you're doing an open source project, since your users need to install Rust to build your program, and there are many platforms Rust doesn't support.

Rust programs use unsafe a lot in practice. One of the greatest difficulties I've had in supporting Rust with Cosmopolitan Libc is that Rust libraries all try to be clever by using raw assembly system calls rather than using libc. So our Rust binaries will break mysteriously when I run them on other OSes. Everyone who does AI or scientific computing with Rust, if you profile their programs, I guarantee you 99% of the time it's going to be inside C/C++ code. If better C/C++ tools can give us memory safety, then how much difference does it really make if it's baked into the language syntax. Rust can't prove everything at compile time.

Some of the Rust programs I've used like Alacrity will runtime panic all the time. Because the language doesn't actually save you. What saves you is smart people spending 5+ years hammering out all the bugs. That's why old tools we depend on every day like GNU programs never crash and their memory bugs are rare enough to be newsworthy. The Rust community has a reputation for toxic behavior that raises questions about its the reliability of its governance. Rust evangelizes its ideas by attacking other languages and socially ostracizing the developers who use them. Software development is the process of manipulating memory, so do you really want to be relinquishing control over your memory to these kinds of people?