Something else as I been thinking on this lately. The thing is how will this be delivered to the people? We are not to be going to be seeing this thing (whatever it is) advertised in black and white as the mark of the beast. Taking Rev 19.20 into account, it has to be something that people cannot accept what is presented to them as being the mark, or people simply just take it so as to not feel isolated.
See something about Rev 16.2, the side effects, and this is something that I not completely sure, but does the side effects happen as soon as the person gets the mark? Or this there some delay? These words here - "noisome and grievous sore" could be translated in more than one way, (note some translations either have singular or plural). This tells me there is something foreign inside of those who took the mark that shouldn't be in the body in the first place.
Another thing, it does stand to reason that if we were to experience a trial run before the main event, it also stands to reason we would be seeing people having reactions.