I think there is a difference between hiring someone with C# experience for a Java role, or someone with C++ experience for a Rust role, and hiring someone for a diametrically opposed software stack. There is nuance.
Though I would say someone with at least intermediate abilities in half a dozen languages has a great track record for learning new things. Carpenters are not sifted for how much experience they have in soft woods, hard woods, or plywood.
Still. I can see hiring someone with 5 yoe C# to serve as the Senior on a Java project. However, I wonder about hiring someone with 5 yoe C# to serve as the Senior on a Java project. There would have to be some sort of additional major value add (e.g., domain expertise).
At 15 yoe C# experience this starts to make a lot more sense.
Though I would say someone with at least intermediate abilities in half a dozen languages has a great track record for learning new things. Carpenters are not sifted for how much experience they have in soft woods, hard woods, or plywood.