So you are saying that because we need to do validation in a very specific case, we should just throw the towel and do validations every time?

The IO entry point of your code will always be unknown no matter what programming language you are using. In typescript, you do validations in these cases to make sure outside data fits into your type system, from then on (probably about 99% of the rest of the code) won't need any validation whatsoever because the compiler is already doing it for you.

Bloat is the amount of time you lose doing code review to check if things are possibly null or doing null checks on stuff that is never null or a bunch of other stuff that the compiler will do for you just by writing some minimal types. The compiler does this stuff automatically without getting tired, can't say the same thing for humans.