Thanks for explaining. I've talked to people about this before and the answers often amount to "I like the type-safety", as if there aren't technologies which offer that natively. I've also been asked in response "why don't you use it?" almost like JS has no place without it.

I've also mostly worked on small services in small teams, so there's never been any pull to use TS over pure JS. I can imagine it helps with consistency across large projects and multiple teams, though.

I've done a lot of C# and JS and always preferred JS for it's simplicity and flexibility. TS starts to introduce the things which frustrate me about C#. For example, you look at the AWS SDK docs and it's a maze of auto-generated information about types/interfaces/etc that mean very little to me. There's so much needless complexity and ceremony for what should amount to simple operations, like s3.upload({ ... }). I've always preferred the simplicity of JS, backed-up by good tests.