That doesn't happen all the time, just a frustratingly high percentage of the time. The problem is that there will be some good players in most tribes, the ones that manage to perform in a war (point whores as well unfortunately), who the victorious side will see as a good addition to the team. Unfortunately some tribes seem to loose sight of the 'keep the good and eat the bad' mentality, although it could just be that they are taking in players so they can be guaranteed that their tribe eats them and another tribe won't steal their winnings. In the end if you don't like all the recruiting that's going on then try and make a difference by attacking them for it, if you win then it'll prove your argument has some merit to it.