I think you're confusing the fact that Reddit leans classically liberal in matters of free speech and personal autonomy with the notion that it also leans economically libertarian. There are, of course, plenty of free marketeers here, but I think they're in the minority relative to the lefties, and I think that there's a huge area of ignored overlap between the lefties and those who take issue with people like Anita Sarkeesian.

The conflation makes less sense when you consider some of the less controversial heroes of Reddit: Carl Sagan or Neil DeGrasse Tyson (both of whom would advocate for empirically-derived, testable solutions to social problems), Edward Snowden (and all he represents with respect to personal liberty), Bernie Sanders (who is the very definition of a progressive social democrat), and so on.

So a left-right binary is unhelpfully reductive, in my view. The political compass is inadequate in so many ways, but it remains a better tool for describing ideological trends because it at least prompts us to consider what kind of a role authoritarianism should play, and in which areas. Movements like GamerGate, for example, lean left on almost all social issues despite protestations that they're a bunch of mewling neocons or traditionalists, and many within said movement would identify as social democrats or even pro-justice, egalitarian progressives in important respects (even if they might take issue with the idea of "social" justice in its contemporary incarnation). This is a generalization, but the principal difference between these people and the oft-described "social justice warriors" of the modern internet resides in which means they endorse toward which ends.

One can easily be in favor of strong market regulation, wealth redistribution, large but efficient governments which ensure that all basic needs of a population are met, etc. while still remaining in favor of due process, open debate, free speech, personal privacy, optional decentralization where applicable, and the necessity of a free marketplace for ideas and tastes (even if the capitalistic market which mediates our access to many of these ideas and tastes must be effectively regulated via progressive economic policies).