This is junk. Writing a type annotation takes basically zero time, then saves you time by preventing the runtime error because you forgot which variable was which, then saves you more time by autocompleting the correct list of valid methods when you hit dot.
Acting like Go is comparable to JS is ridiculous; Go's type system is the only kind of type system needed in Ruby. Rust is a staggering outlier in complexity. And the Turborepo port took a long time specifically because they tried to port one module at a time with C interop between the old and new codebases, which massively slows down development in any language, especially Go. This is just about the most dishonest 'example' you could have picked.
Either that or you are saying 'weakly typed' to mean type inference in `var := value`, in which case (a) Rust has that too and (b) that's not what the debate is about, nobody is against that
Making the type annotations pass restricts you to writing more bloated and verbose programs in general.
Stating that A is an integer isn't much of a issue but once you get a reasonably complex program and A now has a compound type made of 5 parts, it really does slow you down and it really does make you write considerably worse programs for the sake of passing a type checker.
Any commercial code will need to be unit tested so there is no time saving from finding runtime errors earlier and an any good IDE will detect the same errors and provide you with the same auto complete automatically for free without any type annotations at all. These are problems which exist solely in your head.
1 developer vs a whole team of developers. I think you need to face the facts.
There are studies comparing old dynamically types languages against statically type languages. They always show approximately 1/3 of the lines of code being used with 3x faster development times in the dynamically types languages. This isn't some new discovery.
Well even Python is strongly typed but for the sake of this we are discussing type complexity.