Because they know what we want and you don't
This. I haven't played in a good while, but before I stopped I noticed most of the servers that were generally popular were by vets such as myself, Crown, Tezuni (ugh), etc.
Most of the newer players also don't have the experience to run a successful server, such as choosing trustworthy and competent administration, troubleshooting issues, and one of the big ones is just contacts, as in knowing people who specialize in certain things. I had friends who would do the majority of building, scripting, eventing, and administrating etc. that kept my servers running smoothly.
But on top of all that you gotta know what people want to play.
That's just my personal opinion on the topic, could be wrong but that's how I see it.
Kind of rambled on, but its been awhile since i've really posted on the forums.