The Big Bang Theory : why treat Stuart so badly

They are always whining about how they got bullied and pick on u007fand didn't get invited to things and they turn and do the same thing to Stuart.

It's because they got bullied and picked on that they do so to Stuart.

Lesson from the times: Never trust an alligator to drain the swamp.

Pecking order. Poor, hapless Stuart is at the bottom. I'd rather they did it to Barry Kripke, whose behavior deserves it. But he probably was bullied as a child too because of his speech impediment.

Why would they treat Stuart any different than they treat each other? It's all part of the bonding ritual.

One of us.
One of us.

It's Stuart's purpose.

BBT needs Stuart badly for comedic purposes. Some of the other larger relationship or family plot lines aren't so funny. To me at least.