I respect the positions of the mods and admins on this issue, but I think just having an "I agree with this post" button as a standalone could be good where you could hover over an icon and see each user who agrees. I think this keeps accountability while also circumventing the issue of having to make a reply every time you just want to agree with something. And then if someone disagrees, they still have to make a reasoned argument in a post disagreeing.
