Unexpected productivity boost of Rust

The main difference between Rust and other languages with a Standard ML influenced type system is that Rust has features that can let you get executive sign off for switching languages.

what is the main advantage of Rust over OCaml for most applications in this respect?

Not really, at my job Scala, F#, Swift and Kotlin are possible, and most likely will never do Rust, other than using JavaScript tools written using Rust, just because.

There is nothing in our domain of distributed systems based on SaaS products, mobile OSes, and managed cloud environments, that would profit from a borrow checker.

Ecosystem. It's much easier to find libraries for Rust.

opam has plenty of libraries, we should not mix quantity with quality.

Also we don't need leftpad like libraries, which is the direction Rust seems to be going when I try some some basic application that has like 50 crate dependencies.

Rust is very difficult for most people, so do you think that this advantage outweighs that disadvantage? Is that really the only meaningful advantage if you’re not writing a driver or internet-facing compressor at scale?

You're greatly overrating how difficult Rust is. The wealth of high-quality software being written in it shows many people think it's worth the effort.

most people can barely stumble their way through a one and done Python script