Are we all left-tards here?

Come on now.  Are we?  While I myself wouldn't look for bible-thumping republicans, I think we should at least have a few moderates or radicals like libertarians ETC... 

Or is it the disproportionate european population here?

"Moderates" in über-right-wing USA are "moderately" right-wing (i.e. the Democrats). See their position on unilateral pre-emptive carpet bombing (on the slightest suspicion of having oil or having higher than acceptable levels of melanin).

"Libertarians" traditionally refers to Libertarian Socialists, otherwise known as Anarchists. In the US, it regrettably refers to the Ayn Rand lunatics known as the Libertarian Party. They claim to oppose domination, but what they advocate would replace government with undisguised corporate domination. They're basically pot-smoking über-conservatives who want to build shrines to Wal-Mart.

I think there's likely a disproportionate amount of people on 4chan who are not as immersed in mainstream American brainwashed culture, simply by virtue of watching anime. Being exposed to the social values of another culture tends to make you less narrowminded, and therefore less conservative.