Most servers do not need a fancy user interface. They don't have monitors attached to them. Most of the other OSes you listed come bundled with a ton of user experience software along with the expectation a human will directly interact with them.

Servers are typically deployed and managed with automation, by the thousands. Lean. Simple. Secure. Tuned for their specific purpose. This is a lot easier to do with Linux than an all purpose general use personal computing platform.