The problem for me is that you can't ever irrevocably remove a feature from the language, which means you'll end up having to read and interact with code written in the original version if you spend enough time in the language ecosystem. I've seen developers that continue to litter their codebases with `var` in 2024 despite `const` and `let` replacing almost every valid use case for `var`.

Server side developers yearn for their favorite language in the browser, but are used to living in a world where language deprecations mean "this feature will disappear from all modern version of the language eventually" not "you can opt-out of this feature by placing a string somewhere in your code". To me that's a hollow definition of 'update'. Golang for example completely changed the semantics of for loops this year [1]. Moving forward, if you use a modern version of Go, you will accept the way for loops work now — there's no magical 'use old for loops' string. It's awesome that they were able to unilaterally make a breaking change to the language and force users to accept it moving forward. We can't do that in JS, that's the point I'm making.

[1] https://tip.golang.org/doc/go1.22