That looks like mind-numbing garbage that should be kept out of the reach of children.
This is a weird criticism, learning type declarations will not make someone worse at programming or rot their brain. It's mostly just syntax.
As a point of comparison, Scratch doesn't let you assign object instances to variables. I just can't imagine getting worked up about type declarations in comparison to that.
> for a world that mostly no longer exists.
Also... casting no longer exists? I still do explicit casting in JS on occasion, and it certainly comes up in C-like languages. Correct me if I'm wrong, but I don't think Rust even has implicit type coercion at all.