Not true. I picked up a git repo 18 months old. I tried to set up my rust dev stack to match the version in cargo. Then hit a lot of issues with dependencies due to abandoned repos used for the crates. I gave up and moved on.
A random person on github abandoning their pet project is not the kind of language stability we're talking about here. It's not the kind of complaint you'd write to the ISO committee.
You may have run into a project using nightly Rust, which is an explicitly unstable version for testing of experimental not-yet-finished features. Using it requires users to intentionally opt out of having language stability. C++ also has GNU and Clang extensions and experimental implementations of not-yet-standardized features.
However, the normal workflow is using a stable version of the compiler. It is backwards compatible with the 1.0 release from 2015, except handful of edge cases that you won't run into an average project.
Users are encouraged to use crates.io and keep Cargo.lock which guarantees they get the same dependencies that worked last time.
It shoudn't even be anywhere near an adult for that matter. Even a trained operator wouldn't be putting fingers where there was no safety interlock.
for example, two buttons you must keep pressed with both hands before the robot starts to move and will stop immediately once you prematurely let go of it.
