The previous forum software used to have stars next to member names, and people would vote that way. Obviously, any open voting system is open to rigging as well (like multiple voting, phantom voting, etc.). A juried system would make more sense, but then again, there would be no end of complaints of favoritism, unfairness, etc. Not to mention the amount of time it would take for the moderators.
I am not saying what you are suggesting wouldn't make sense, just that it is rather impractical. As in many other areas of life, it takes a bit of getting to know people, before you could trust their judgment.