The productivity cost is mostly up front, once you understand borrowing it's seriously not bad in 99% of cases. Also, you can be initially productive in C or C++, but how much time goes into trying to fix undefined behavior, threading issues,etc. More importantly, when do those hours get spent? Is it after a customer is screaming into your support chatbot, or is it before you launch during normal development? To me that's the difference and the killer feature. That's why ms, aws, etc are using it. Not because it's new and marginally/debatably better then c/c++.
Once I started realizing what the borrow checker was saying it wasn't "fighting the compiler" I realized what I was asking the compiler to do was really not a good idea. It becomes your friend basically.
I didn't make this post to shill rust, I'm pretty language agnostic to my own detriment... The point is, it's worth considering and trying it again if you didn't get it the first time around. Rust took me 2x to become a tool I'd use, I honestly hated it at first.
