When a group lists what is wrong and votes on what matters most, the winner is almost always the thing everyone can see: the waiting times, the outages, the complaints. Those are consequences. The causes sit further back, spread across people who each saw a different part.
True Causes lets the whole group find them. Everyone writes causes alone and unnamed. Then the group answers one question at a time: does this cause significantly influence that one? A link counts only when three quarters agree. What comes out is a map, deepest causes first, with every disagreement kept on it.
Many small rooms can take the same question and fold their maps into one, so a hundred people can do what used to need a hall. In simulation, a room that ranks by what it feels names none of the real causes; the same room, mapping, with a few seats kept for evidence, finds most of them.