As much as I despise how close-minded and backwards society is on average, this particular argument doesn't hold. What you see on a social networks is not a likely to be valid data-point for what the average person is like; at the very least it will be heavily biased. SMBC has a very concise explanation:
http://www.smbc-comics.com/?id=2939
Of course that's just nice a hypothesis/observational humour mix, but it fits with the well-known effect of people thinking the world is a lot worse because the news reports only the negative, or that everyone else in their (virtual) social circle is more happy and successful than them because Facebook shows the most liked posts first.