Earlier quoted context omitted.
It's totally normal except for C/C++ toolchains on Linux . C/C++ compilers are managed this way on MacOS, Windows, and by most embedded toolchains. Why don't you want your toolchain managed outside your distro? Don't you want your software to run outside your distro?
Longing for a more stable world doesn't sound very weird to me. Maybe core Rust development will slow down in the future.
And if you stop updating those, you stop needing rustc updates.