Here's an anecdote to provide sense. I recall when I was using a 3 month old (1.48.0 2020-11-19) rustc on Debian 11 (right before it was officially released) and I kept running into rust software I couldn't compile because rust devs used bleeding edge 1.50 (2021-02-11) features. This wasn't a debian is old thing. The rustc was literally 3 months old at this point. At least one of the devs was a person I knew on IRC. He was kind enough to re-write it ("plotsweep" a rust software defined radio program) using only 1.48 and older features. But that's the exception. Most rust devs assume your toolchain is from 3rd party out-of-repository and latest and think forwards compatibility is useless like you do.

Shell scripts can be and often are jank. But at least it's stable jank. Shell devs tend to write portable, stable code because that's the entire point of dealing with the shell jank.