Sometimes questions which aren't appropriately formed according to the site guidelines get a lot of down votes. I would not normally up vote these questions - but I don't feel they are necessarily worthy of so many down votes. So is it then considered okay to up vote the question purely to cancel out the down votes? Or does this somehow defeat the purpose of the system?
In principle, the point of a voting system is to gathers information about everyone's opinion on the question, not just yours.
Voting to cancel out downvotes very much goes against this — in effect, you are saying your own moderate opinion on question is so valuable that you will go out and erase someone else's negative opinion on the question.
Not to mention this is a very disenfranchising action; there are already a number of barriers in place towards downvoting:
- The reputation cost (only relevant to answers)
- Peer pressure into believing downvotes are 'bad'
- Aggressive reactions from people receiving the downvote
It can be quite distressing for someone who is affected by these things to go out and down vote something they think deserves it, only to find someone decided to cancel it out. So, the person suffers from all these negatives without their voice being heard — and even worse, the net result is positive feedback to the recipient of the votes. (upvotes give more reputation than downvotes subtract)