Who says they are? Probably depends and varies by the application. One example I could think of is if it's currently a SaaS on Azure, but it needs to be portab

Who says they are? Probably depends and varies by the application. One example I could think of is if it's currently a SaaS on Azure, but it needs to be portable enough for a version to run in a low end Arm IoT device. Or if it's deployed to thousands of servers and taking excessive memory or CPU resources for a monitoring agent. Or GC freezes affecting other adjustments systems. There are plenty of reasons to retire C# to Rust.