It would defeat secret ballots.  If you had any ID'able information on a ballot it would let D operatives know how you voted and then they could send people to intimidate you, or worse.    The entire point of secret ballots is so you can vote without fear of reprisal from the despots in power.    Otherwise it ends up like "Soviet voting" where you voted for Stalin or a week later you were sent to a gulag.  But secret voting cannot be done by mail or by internet.  ANY kind of tracking on the votes cast would let despots like Pelosi know who cast what ballot.  And they WOULD retaliate against people who voted against her.    So the only "solution" was to control who got their hands on the ballot cards in the first place.  But of course with no way to verify the ballot with votes on it was lawfully distributed, its was effortless to "find" trucks full of mail "votes" when the election was called into recount the day after a republican won.    So voting HAS to be in person, its the only way to secure it.