imo redditors and 4channers think too highly of themselves if they believe they have real influence on elections. Most people aren't online (except for Facebook), and politics are much more readily explained by material causes such as the Dems fcking up the post 2008 economic recovery and going for austerity instead of investment. The biggest proximate cause (non-material/economic) is just that hilldawg ran a bad campaign that didn't focus enough on swing states (but she won the popular vote, congratulations).

There have been dark corners of the internet for several decades now. 4chan is just one. Trump didn't achieve popularity because of it. There aren't enough users, and there certainly aren't enough politically and economically influential users, for that to be true.