[kristiandupont]

Sure, the TS type system is not sound but the idea is not to stop "bad guys", it's to help you realize you are doing something unintended.

[jwalton]

This is very true, but "helping you realize you are doing something unintended" works just as well with a string as with a symbol.

[presentation]

Agreed, for instance in our codebase we just make all type assertions a lint error demanding a justification, as well as flat out banning the any type. But anyone is free to write shoddy TypeScript.