That's because one is a service, and one is an open operating system. If a service doesn't support a protocol, you can't use that protocol with it, so there is demand that the service support the open protocols that most clients have implemented. If an open OS doesn't have built-in support for a protocol, you can choose to add it. It's apples and oranges. It's like saying your laptop doesn't support a particular printer because you have to install a driver to print.

For an OS, it makes more sense to err on the side of supporting fewer protocols by default and allowing users to clients to add the ones they need than bloating it up with all possible protocols you ever might want to connect to on any server, anywhere.