Why is there a bias against MP only games?

[Peh]

I'm getting bored really fast with MP only games. I buy the game.. play for the first few days and then switch over to the next game. From time to time I'll get back to it. Currently I am only playing BF4 from time to time. There is no other MP game that interests me. Maybe Splatoon.. once in a month or Mario Kart 8, but you can't consider them MP only.. or maybe you can...

But on the other hand,... I am not much into Multiplayer games. I prefer SP.