I don't think so. If you have open source voting machines that can be and are audited, that's probably more than good enough for fair and open elections.
Lowering the complexity and thus barrier to understanding just builds an extra buffer of transparency into the system. It's a very-nice-to-have.
In a technical sense, yes. But there is definitely social value in having a system that is in principle auditable by (almost) everyone. An open source voting machine would still be only auditable by the small minority of people who can read code.
You don't want to just have free and fair elections, you want to also convey the clear and unfakeable impression that your elections are free and fair.
Pen and paper gives you both a safety margin (or transparency margin). And it allows you to signal in a hard to fake way that your elections are free and fair and hard to temper with.
(Fair as far as the voting system goes. Eg first-past-the-post on paper will still be a less fair voting system than Germany's weird proportional hybrid or my favourite, range voting. Or this fascinating gem: https://rangevoting.org/PropRep.html)
Lowering the complexity and thus barrier to understanding just builds an extra buffer of transparency into the system. It's a very-nice-to-have.