This site has never made clear what the voting is for. I used to use it for strongly agree/disagree. Then it was changed because someone complained they'd been downvoted on all their previous posts so only up arrows exist on old posts. Since I read interesting looking articles that appear in RSS I only read old posts so this effectively barred me from participating. Dropping down arrows was a poor solution to the problem.

I then realised that the remaining up arrow could be used as a `I've read this post' indicator and started clicking all of them as I read old posts. Very useful to help pick up reading where I left off. Funnily enough, I'm not aware of anyone complaining that they'd got lots of up votes over the period I was doing it. :-)