Also the OCaml community is miniscule compared to Rust. And the syntax is pretty bonkers in places, whereas Rust is mostly sane.
Compile time is pretty great though. And the IDE support is also pretty good.
> even older than Rust
That's an understatement, (O)Caml is between 17 and 25 years older than Rust 0.1 depending on which Caml implementation you start counting from.