In my younger days I thought direct democracy was unworkable, but now I realise that might have just been my brain conforming to the bourgeois representative government status quo.
Obviously we easily have the tech to do DD these days, everyone has a smart phone in their pocket, we could do it instantly and on the go. But how you could manage a planned economy that way I’m not sure.
One problem with it is the sheer amount of compromised hardware, the vast majority of people would have no idea whether or not their phone is infected with malware
Another is simple man-in-the-middle attacks, which have been declining as net security has got better, but they are still possible
Another is that attacks on paper ballot elections are not easily scalable, if you want more impact, you need more people, and more people means it's more likely that the scheme gets blown wide open. Contrast with an attack on an e-voting election, which is very easily scalable, a single talented hacker half a planet away can change a million votes just as easily as they can change 20
And if it isn't using the internet to electronically vote, then what's the point? Turning up at a polling station to press a button on a machine is no more convenient than marking a piece of paper. Voting machines are basically a big, expensive, hackable pencil.