There are two things playing here:
First, ascendancy has an invitation system which has remarkly low and high standards at the same time. If you are a proven shit player, you do not get in. But about anyone else gets a chance. If you are a proven proper player you get a chance as well. Which basically means that anyone being propped get in. Apart from a few 'well known cases'.
Second. Ascendancy is apperently the best alliance around which no other alliance can take on one on one and multiple alliance need to gang up on ascendancy to take them down and make sure they are not of any influence in the
end game (we havent addressed the end game enough. Exponential growth and end games make for interesting research). As a last point I wish you all to read up on
this and hopefully you understand why hitting Ascendancy for a prolonged period of time will never work when working with people acting on rationale in stead of zealousy.