It is worth noting that Russia's goal with its initial propaganda efforts was not necessarily to elect Trump, but instead to sow dissent against a likely Clinton presidency. This included a heavy pro-Trump campaign, but also a sizable pro-Sanders campaign. Therefore the extremist views you see on Reddit on both sides of the aisle have likely been spiked by Russian propaganda. I'm not saying Reddit doesn't lean liberal, just that the "ultra-liberal" side of the site that appeared during the 2016 primaries might not be completely genuine.