As simple as it may seem it all turns on the placement of the comma.
“The vestment of the deacon is the dalmatic, over the alb and stole” is different from “The vestment of the deacon is the dalmatic, over the alb, and stole.”
As to what drives people to abuse the liturgy? For many it’s just what you are doing, going along with what they’ve seen done, either because they don’t know any better or because they are not willing to stand up and say “I’m not doing that because it flies in the face of rubrics.” For others, it’s the hubris of believing they know better, plain and simple.
I once brought up the fact that we were, against all the rules, using EMHCs to distribute Communion in my parish while the 2 concelebrants sat and watched. The pastor got very upset and said that Redemptionis Sacramentum had not been implemented in our diocese and I shouldn’t be quoting from it. I replied that RS, in this case as in much of what it contains, was not imposing a new rule but was simply restating what had already been said in three previous documents, starting with the one that allowed EMCHs in the first place. The assistant pastor (who had long ago been the pastor’s seminary professor) got up, shook his finger in my face and yelled “We’ve never paid attention to those documents before, we’re not about to start now!” THAT’S the kind of hubris that leads someone to abuse the liturgy.