If there were a lot more conservatives or libertarians, the OP might not think there are a lot of communist posters here. Because there are a lot of left leaning people here who upvote anti-capitalist posts and comments, it is easy for the OP to reach the conclusion that there are a lot of communists. My three points explain 1) why the platform was already predisposed towards leftist thought in general, 2 and 3) why there are not a lot of right leaning ideas to balance out the ratio.