Fptp is illogical but it cannot be changed by dialogue

It's not possible to convince someone that fptp is a bad idea. The reason for this is that their belief or support for fptp does not lie on any foundational assumptions... it is merely what has always been. They will often interpret someone wanting to change things as a revolutionary and not a libertarian. Since support for fptp doesn't rest on any principles it is not possible to convince people to change it.