I don’t think it really fractures anything considering you can call a ts package from js without knowing. The other way also works with third party typings in DefinitelyTyped.
It really just adds a bit of extra type info into js, looks like js, and transpiles into js that looks almost exactly like the input, including comments and spacing and such if you like, so there isn’t any lockin.
There isn’t any competition, it’s just an extra optional tool for the js ecosystem in my eyes.