In the last generation, Sony didn't really have to buy off anyone for exclusives because it's userbase was so big, it didn't have to worry about the competition. The generation before that, Sony didn't have to again either because Square came to them with FF7 since they liked the disc better than the cartridge. Thus, their rise to power. And the one before that Nintendo didn't have to worry about Sega because let's face it, everyone loved the NES/SNES more than the genesis.
It's safe to assume buying off exclusives and studios wasn't so important back then because all of the third-parties can choose who they want and they chose the one that the consumers want obviously.
That was, until Microsoft came into the picture in 2001 and with it's load of cash able to buy exclusives left and right. They happened to have found their own S-E except in America, called bungie and immediately bought them off just so Sony couldn't get its hands on them. I believe Microsoft entering the gaming world made any competition realize now that if you don't have the cash cow to buy off exclusives/studios, you aren't going to out-bid them.
So now this gaming world will forever be about who has the money to buy off exclusives or studios and it already started since the last generation. Now third parties have to deal with hard decisons whether to be bought off and risk losing an audience.
