We have to, in other words, view present GOP behavior as symptomatic of a political system which in the first place allows it

If, as you say, the system allows it, we must therefore ask why it took the system some 230 years to come to it... ?

Representation is representation. They are not delegates. They are not puppets. We invest them with great power and try to ensure they don’t abuse the power. The GOP is currently abusing their power. This is not a fault of the system. It is a fault of the amoral who abuse the system.