Featuring Nikita Bier, Joe Previte, Rapid, James Leighton, and BeeJayDeL
Regarding Typescript, I think you're a little off the mark. For me, I think Typescript is a tool that helps me wrap my head around just what exactly is going through my JS code. There's so many various shapes objects can take, and it actually speeds up my development if I can know up front what the data going through my code will look like.
More generally, the tools I use need to match how I'm thinking through a problem. Maybe your brain is more JS-oriented, and mine is more Typescript-oriented? I don't know. I just know that TS can help correct this impedance mismatch I have between my brain and JS, and through that lens, I think it's useful even for a brand new prototype project, not just rock solid production-level code. It helps me stay organized and think through problems.
It's also worth mentioning that typing with Typescript can be incremental, that you don't have to type absolutely everything up front. So you can add types where it makes sense, where the pain points are in your code. The example that immediately comes to mind is date/time parsing and formatting -- I mean, how many different formats can a date/time go through?