Because sometimes its as if people look for things to be offended at, instead of actually being offended. There is a big difference between a bigot and someone who thinks 'SJWs' are extra
Also i think one of the reasons that people get annoyed with 'SJWs' is because of the aggression shown by them online when someone disagrees with them and also the morally superiority that comes with them. No discussion or back and forth, just 'your wrong and the worst person ever, while i am righteous' kinda thing.
In schools here, teachers arent allowed to say blackboard anymore in case it offends someone. This isnt doing anything to help combat racism, its complaining for the sake of complaining.