If I had to guess, I'd say the internet hates people in direct proportion to how little effort it takes to offend them. I don't say that to imply that the victim should be blamed here in any respect. I just think the primary motivation here is an opportunistic desire to offend rather than genuine dislike of certain groups, so these people are going for the familiar, the low-hanging fruit. Then again, maybe all genuine categorical hatred is opportunistic at its core...