Linux doesn't solve the problem either, with the ability to replace open files. It just means you run into potential compatibility issues if you modify a shared lib and then two processes try to perform IPC that might rely on false assumptions (I believe this is exceedingly rare in practice) and to update kernel components, long-lived services you still need to restart them.
You can perform hot updates to a system but it can be complex and there are a number of restrictions on the types of updates that can be done.
You can perform hot updates to a system but it can be complex and there are a number of restrictions on the types of updates that can be done.