Most of Rust's difficulty comes from the borrow-checker. And if you're mostly doing linear work, if you're doing a lot of math, if you have a lot of pretty flat data structures, if you mostly keep things on the stack, then you may not run up against the borrow-checker that often. I would assume (I don't know for sure) that scientific computing tends to do more of this kind of stuff, and not as much heap-juggling/heterogeneous data modeling as, say, a web server.