Strikes me as a lot simpler to have a system where, once you are on the electoral register, that's where you are entitled to vote until it get updated, or until maybe you yourself apply to get it amended, because you have relocated to a different part of the country, and want to be able to vote there instead.

Putting decisions about this kind of thing into the hands of politically motivated people, who are prone to care a lot more about achieving victory rather than defending democracy, seems like a pretty serious error. It's asking for trouble and corruption, and it's not surprising if it achieves those things.