Because its fun to argue, and most people don't have enough money to buy 3 $3-500 consoles, plus a $400-$2000 PC, so they can only choose one.
That and not everyone has a use for both. I have no need for a console. The exclusives don't interest me, I have nowhere to put one, and everything else I can do on my PC better. Some people have no need for a gaming PC, not having room for one, and not being interested in the games it plays.
I will agree both have their place though. It all depends on the person, and if you're one of the people that has a use for both, more power to you.
That and not everyone has a use for both. I have no need for a console. The exclusives don't interest me, I have nowhere to put one, and everything else I can do on my PC better. Some people have no need for a gaming PC, not having room for one, and not being interested in the games it plays.
I will agree both have their place though. It all depends on the person, and if you're one of the people that has a use for both, more power to you.