If the voting process was made as simple as possible (taking into account the best available evidence from user testing, psychology, linguistics, and so on) and

If the voting process was made as simple as possible (taking into account the best available evidence from user testing, psychology, linguistics, and so on) and someone decided to deliberately disregard the instructions given, and avoided all efforts to be educated on the topic, then at that point I would agree that the individual's agency was at fault. To be clear, I don't think that such an individual would "deserve" disenfranchisement as a "punishment" for their actions, since voting is a fundamental right that needs proper due process to remove from someone; it would just be an unfortunate practical consequence of their poor decisions. Let me reverse the question though: Is there any point where you would concede that the voting system was unacceptably flawed if it caused one or more people to mistakenly fill out a ballot that didn't reflect their true intention (or made them choose not to vote at all)?