I shouldn't have said it's a waste of time period, cause every project I work on does have static typing in two very important places: the RPC or web API (OpenAPI, gRPC, whatever it is), and the relational database. But not in the main JS or Py code. That's all I've ever needed.

I did try migrating a NodeJS backend to TS along with a teammate driving that effort. The type-checking never ended up catching any bugs, and the extra time we spent on that stuff could've gone into better testing instead. So it actually made things more dangerous.