No it's not, Ellers. Technically, you don't even vote for a party. You vote for an individual who then goes to Westminster and represents your local area. After all, Carswell wasn't forced to resign his seat when he moved from the Conservatives to UKIP, was he?
The 2015 Conservative manifesto included the promise to stay in the EU and to hold an advisory referendum regarding leaving it. Only after winning the election in 2015, and when campaigning for the referendum in 2016, did the government say they would abide by the result of that advisory referendum. That is why some people (me, for instance) think we should have a general election now - to legitimise the new unelected government, staffed by many MPs who were not in the frame to run the country in 2015, being backbenchers or out of step with the party leaders.
The 2015 government no longer exists. We should have a say in who governs us and how they do it.