> 1. We're going to be year(s) behind. I need everyone to learn and be proficient at the languages we use. They need good consistent doc and manual for our version. And not complain that we're on 1.31.0 but this great feature is in 1.33.1.

    rustup doc

gives the standard documentation (book and API) for whatever version is currently active. You should be able to install and default to any version of the toolchain you want e.g. `rustup default 1.31.0` and you're done

> And not complain that we're on 1.31.0 but this great feature is in 1.33.1.

Surely that has nothing do do with Rust's evolution, and happens on every language which is not literally dead? Even on languages with a relatively slow release schedule this happens.

You mention Python, that's what we use at $dayjob, we're currently on 3.5 compatibility. Some colleagues would like to use f-strings, or walrus, or dataclasses, and they can't and that's life.