You're right if (like truthers) one doesn't actually have said evidence or the evidence is flawed.
However if one does actually have solid evidence of a great injustice... Well, I have the right to vote, my wife has the right to vote, hell we have the right to be married in the first place (and much more) because people did what I mentioned.
Granted it was many people, and it took time, but the truthers claim numbers in (at least) the thousands.
Point is, truthers seems more concerned with showing up debunkers on web forums than doing anything that would effect the real world.