We do this at my current company for all projects, it does not mean you don't use typescript, you will still validate all your files with TS, but there's no build step, just a check.
Very rarely we find a case that we can't cover with JSDoc annotations, and most of the time it means the code could be refactored to be simpler.
I do this now for all my personal projects, in my opinion it's simpler, faster and closer to pure JS.
This is great but -if I dare - wouldn't it be time to allow js to have type annotations [1] ? As in python, treat it as comments for now but with real syntax and let interesting dialects emerge from the consensus ? I like jsdoc but the syntax is urgh.