While all votes should have a valid RFD, there will always be some bias in our thinking. A 7 point vote is a votebomb (even if occasionally valid), and will usually be countered. Thus the more strongly you support a side in a debate, is the more reason to not click any category other than just argument.
(this is not to say all 3 point votes are valid)
In DDO voting, 3 is not of greater value than 7, because 7 is the greater number. DDO voting is no different than any other voting system, where the greatest number of votes wins. Because three is a smaller number than seven, seven by definition has a greater definition. It is the larger number, which has the greater value than three.