I work in a codebase that unfortunately does not support TypeScript. I use JSDoc extensively, although not with type check enabled (due to various limitations). I also work on other projects with TypeScript. My own experience is that the DX with "real" TypeScript is much, much better than JavaScript with JSDoc, without question. JavaScript with JSDoc is much more verbose, with a lot of limitations when types get long or complex compared to TypeScript. The official TypeScript language service also does not provide the same level of support in very subtle ways.
Basically, the fact that it works does not mean it works well, and I don't recommend anyone going in this other direction unless they understand what they are getting into.
Not a limitation in language service, but an issue with the codebase itself -- legacy codebase with a lot of missing/incorrect typing from upstream JavaScript code (owned by other teams), making it practically impossible to actually run type check.
Basically, the fact that it works does not mean it works well, and I don't recommend anyone going in this other direction unless they understand what they are getting into.