If you're using Babel for compatibility with particular browsers then that can already handle TypeScript. What distinction are you drawing between a compile step that "strips away the type annotations" and one that does something else - what else is it that you consider compiling TypeScript to include?
I have to ask what you're trying to achieve here. Moving types into comments just gives people who build without your typechecker the chance to break your code.
The comment stripping is optional (just for saving bytes on download). The goal is moving away from Babel, and any other unnecessary transpiling steps. Now that JavaScript has (a semi-working) module system, I find my projects having fewer and fewer dot files and far fewer dependencies.
If I can have a folder of plain JS that I know will work in a browser 20 years from now without having to resurrect an ancient/abandoned toolchain, then I'll do that!
Are you gonna hardcode all the HTML and CSS as well? I would expect resurrecting a 100% compatible toolchain for a mainstream source format 20 years from now will be easier than resurrecting a 100% compatible browser. Especially if that format is a stricter/less ambiguous one like typescript.
I have to ask what you're trying to achieve here. Moving types into comments just gives people who build without your typechecker the chance to break your code.