The thing is that with the rise of far too many sloppy self-taught developers out there pretending to be working on real world projects, Typescript's so said "type gymnastics" comes to slow them down from making atrocities such as turning the same variable from a boolean to a number to a string and to and array. And mostly, compilation times (transpilation to be precise) is the cost we pay for that.
Vanilla Javascript may work for an experienced development team, but (MHO) not for Stackoverflow copy pasters.