I will also add that Rust is not trying to be C (and neither trying to "replace C"). It's here to offer an alternative, that in some cases makes more sense than sticking with C. C code means a lot of thing. For example, some people code in C89 because they find some kind of purity in it. You're never going to get that from Rust. For some people, it means fast and secure code, like with Python's cryptography. That's a place where Rust can be used. For some other people, it's C because that's the only thing that's allowed by some authority. Again, Rust isn't going to fit here until/if it's allowed. I think in general, trying to reason in terms of use case leads to better comprehension than trying to think in languages.

But outside of that, the move was basically the same. They found another language that's very similar, but that has a way bigger ecosystem.

When I think of OCaml, the concepts that come to mind are brilliant French computer scientists and hedge funds. A practical Haskell. When I think of F#, I think of... .NET, bright enterprise programmers who want to work with a tolerable language, and that's about it. If forced to name a user of it, I'd say "uhh, no idea... Maybe Stack Overflow?"

(That's entirely aside from the relative merits of both languages, which are leaps and bounds ahead of both most OOP and functional languages.)