I don't think it's possible to completely disconnect the two.
Football, particularly at the highest level, has normalised abuse of match officials as being a part of the game and it empowers the dregs of society to dish out the kind of abuse we're now seeing. It filters down to grassroots, so it's hardly a massive jump to think that it has an impact on what fans think is acceptable too.
It is far from just referees though. Players get abuse on social media from so called supporters when they make an error, commentators and pundits get it when they say something fans don't agree with about their club, just look at the vile abuse Karen Carney got recently for evidence. Referees arguably get less abuse than players online, obviously because they make far less mistakes but also they are unlikely to be on social media, certainly not under their own names anyway.
The sad reality is just that there are some sad individuals in society, and they are cowards as they wouldn't dish out that abuse to a person's face.