You may be in IT, but I'm gonna guess you've never defended a mission critical distributed application / network against every major nation state attacker all at once.

If you implement a vote online system, that's exactly what you would have; China, Russia, Hell even some of our supposed allies all trying to hack their way in at the same time to skew the elections in their favor. And you may know after the fact that there was a hack, but good luck finding what they changed once they have root level access to your network.

Lastly the government is generally terrible at everything they implement technology wise. They couldn't even launch a healthcare website without months of issues and overrun budgets. I don't trust them to develop and secure un-auditable digital systems that determine who is in power.

Voting online is just an all around terrible idea.