You're completely right. Both sides do it and claim that they don't do that, only the other side does it. They both do it just about equally. Most do it for validation of their beliefs on a personal level -- it's a personal satisfaction thing, and a seeking of connection with others, which is a huge driver of human behavior and is well documented in psychology circles. Some seek power from it, and these become the charlatans and cult leaders of the world.

Thinking means invoking higher functions, and it means having the courage to break from the group and rise above your animal instincts. People don't like that, because it casts doubt into their own minds and makes them uncomfortable. I find doing so incredibly liberating and scary as hell, but I can't not do it. Following the crowd is something I can't do worth a damn no matter how hard I try. It always goes wrong when I try, so I've given up.