As someone with multiple citizenships, why would I bother to vote for the country that I don’t live in? Sometimes there are significant hurdles in registering to vote if you don’t have a local address or proof of residency. It’s a big enough challenge to get people to vote in elections of the place that they live let alone everywhere that they have citizenship. Additionally in quite a few places including NZ you don’t need citizenship to vote and can achieve the same with residency which I think is fair because if you live in a country (and pay taxes) for years then you should have a say in political affairs.