Ok so Not EVERYONE is a Alpha Tribe member. but a good chunk of those playing on official servers that are getting shut down are. Because in 90% of the cases the people on these super lowpop server that are getting shut down the server is run by 1 group. This group has gigas, Wyverns and everything else that is super end game and they don't even want to think that a group can join the server and might one day be able to knock them off their throne of being the best on the server so they wipe them over and over and over again untill that person or group of people leave the server. This is what Alpha tribes do. There are servers that have big tribes that rule the server but they arn't alpha tribes because they don't wipe out everyone else they enjoy people playing and enjoy having pvp matches.
There was on official I can't remember which that had 2 large tribes with multiple gigas and they didn't kill everyone they even hosted pvp events. They setup arenas where small groups could go out and fight and the winner would get a mastercraft longneck rifle crafted for them. These guys I would love to see on a new server even if they kept everything they had because they made an official server fun to play on. They even on multiple occasions would watch a raid to make sure it didn't go to far. They would watch as a group broke into a base and stole stuff. If the group started to destory the entire base just because they would stop them and if they droped everything on the ground just to have the other group not have it the big tribe would go in collect the stuff and give it back to the raided person before it despawned.
Thats what I want to call an alpha tribe and if I EVER made in on official I would either want to be on one that played like that or be part of one. If every Apha Tribe played like that it would be someone I would want to help defend in a big raid because thats the type of group I would love to see on a server.