Voting is not a linear algorithm. If it were, Howard Dean might be president if not for a HYAAAAAA

You'd be correct to say it's not the only reason to vote. But it certainly would be a contributing thought in voters minds. Does is sway the individual? Many times no. Many times, it may. There are probably not many voters that it would be a "single issue" for, but if they are politically moderate and getting free cash every month, they may be less inclined to worry about borrowing against their children's future than someone who isn't receiving "extra help" and slightly more inclined to vote for politicians that want to spend the treasury like a 16yo with a credit card.