Lots of Remainers are saying, “We voted Leave to give power to Parliament, so what’s wrong with Parliament deciding to stop Brexit? You wanted Parliament to have supremacy, well, it has it, and now it’s asserting that supremacy, which by your own logic you have to abide by”.
This is completely wrong, though. We voted Leave to give the British Parliament supremacy over the EU. We did not vote Leave to give Parliament supremacy over the British people.
Parliament only has legitimacy as our representatives. Once they stop representing us, and betray our stated preferences, that legitimacy is gone, and they’re nothing more than bunch of self-important windbags in a fancy building.
Any power they have over us in that scenario occurs only by force (and then only so long as they control the Army and the police).