I think you did not understand. It has nothing to do with alliance or ability to do boss, or etc.
I'm talking about the dino limit per tribe being 500, but this number is global, adding ALL the dinos that the tribe owns, even though they are separated between several servers. If the tribe has 100 dinos on a server "X" and 400 dinos on another base on server "Y", then it would reach its 500 dinos limit.
This would prevent us from having tribes with multiple bases, on several servers, full of dinos and taking the server to the limit. There are tribes that have servers full of dodos, lytros and other crap, just to hold the slot to be able to create when it is convenient. But these same tribes have a "main base" where they keep only the TOP of their list of dinos.