Because if I wanted to take the game over a friends/family/significant friend with benefits house I wouldn't be able to go online unless I loaded my PSN onto their system. But I already have my PSN loaded on 2 PS3's, so now I gotta deactivate one of said systems to activate on another. See where I'm going with this?
Or for the simple fact if I have another PSN account that I use and pay for things online with, I can't use the item I purchase because the game only recognize the pass for the first name I registered on. That's how I'm penalized. Because back in the day I didn't have to deal with this absurd nonsense.
The consumers are losers in this situation. And if anyone told you otherwise they're in denial or Corporate Apologist.