This is a common fallacy imho that if I am a good dev, I can easily cross-train.
I have been writing C# almost exclusively for around 20 years and I am still learning tricks/tips/gotchas and not just for new language features. That is why my experience is important. Even in something like Java which looks very similar to C#, it takes a long time to work out what works differently, good patterns and idioms, the correct libraries that everyone uses for stuff etc. even when I know what I am looking for.
When I looked at Rust, I got some of it because I have previously written C and C++ and didn't have a problem with the concept of pointers or references but it still took me several weeks to get a basic example working and I had to ask on a forum in the end.
I have been writing C# almost exclusively for around 20 years and I am still learning tricks/tips/gotchas and not just for new language features. That is why my experience is important. Even in something like Java which looks very similar to C#, it takes a long time to work out what works differently, good patterns and idioms, the correct libraries that everyone uses for stuff etc. even when I know what I am looking for.
When I looked at Rust, I got some of it because I have previously written C and C++ and didn't have a problem with the concept of pointers or references but it still took me several weeks to get a basic example working and I had to ask on a forum in the end.
So yeah, not easy!