How likely is someone going to find a guild to join then join its staying server. As oppose to the usual process of first find a server, then find a guild inside the server only after you found yourself going to be staying in the server and are okay with the rates/economy/community/gm/etc. I wouldn't do that myself and wonder the OP or anyone ever tried that and how was it.
On the other hand, how likely would a guild on a server recruit complete new player to a server, wait for the person to level up and get items etc and then get ready for rumble. Assuming the person won't drop out in the process. If the person drop out, the investment in time or start up item will go to zero. To me isn't it make more sense to hire someone already on the server? If the person is loyal to the guild the person will move with the guild to another server when the time comes. The chance of the new hire going to stay on the server when the guild move is equally likely.