Yeah, "linuxism", that must be it... That or it's possible that the OS and distributions have evolved while you were not looking.
Linux dominates on servers because of that yes. Also because of its licensing costs, being open source, stable, secure (please don't try to tell me Windows is more secure, please please please), better performance and lesser response time. Because a Debian stable will never break with simple security updates. I am also quite curious about getting a source for that claim that Windows Server is coming back.
Finally, do tell me where I mentioned MacOS. Unless you think that MacOS and Linux are the same? That wouldn't surprise me considering your apparent knowledge (or lack of) about Linux. FYI MacOS is based on a BSD kernel.