It basically boils down to purchase justification. If consoles didn't cost $300 a-piece, console wars wouldn't exist. Because of the initial price, most people can only afford one, and once that decision is made, one continues to become further and further invested in their choice with every purchase toward it, i.e. games. The result is that people need to hear that they made the correct pick. When people hear that "PS3 HAS NO GAEMS!" they take it personally. That's their console you're talking about.
Same rule applies to individual games after that. Games are expensive as well. And the console competition doesn't help, especially with some games being exclusives. Eventually reviews are just a leaderboard of, "which game is best", despite some titles being absolutely incomparable.
Ultimately, if DVD/Bluray Players cost more and had exclusive movies depending on which brand you bought, we'd have the same problem in that field.