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.
You're asking two different questions: is a planned economy more efficient at achieving it's goals than a market one, and are democratic institutions always the best way to distribute power, or can there be exceptions?
I think the answer is that localized control is best, and the more democratic an institution, the better the outcomes for everyone involved. Also planned economies are better than markets because we can organize their outputs to target better goals than just "make as much profit as possible right now". Combine those two and you have a democratically controlled planned economy, where the goals of distribution are set by the people who live within the economic system. Then it's just a matter of creating the most democratic control mechanisms possible.
That’s what I’m asking though, what is the most democratic control method possible, that is still workable?
I wrote out a whole thing but someone else's "liquid democracy" idea is basically it, but also abolishing the presidency and senate, and somehow overcoming the internet voting problem.