> You can, in theory use very strong lint rules (disallow `as` operator in favour of Zod, disallow postfix ! operator), but no actual codebase that I've worked on has these checks. Even the ones with the strictest checks enabled have gaps.

That's surprising. I've worked on a few codebases with reasonably mature TS usage and they've all disallowed as/!/any without an explicit comment to disable the rule and explain why the use is required there.