Well… I have. I helped bootstrap the TypeScript community in Ember back in 2017 (it existed before that, but I pushed hard and slowly pulled together a small team that works on it). I've written ridiculously advanced types with TS to solve problems (and experienced the compile time pain that can come with that). I'm deeply familiar with TS's strengths and weaknesses. I love TS. I'm working on paving the path to land it in one of the largest JS apps in the world. So when I say that Rust and Elm do things TS doesn't and can't, I'm speaking from experience. Lots of it! And that's not a dig on JS (or C), which I do actually like. It's just that I see how things can be better, and look forward to a world where we have yet nicer things.