I'm just tired of the signal pollution, and would like to be able to use karma to honestly appraise the worth of my articles and posts, without seeing 80% of my downvotes come in chunks that correspond precisely to how many posts I've made since the last massive downvote spree.
EDIT to add data points:
Spurious downvoting stopped soon after I named a particular individual (not ALL downvoting stopped, but the downvotes I got all seemed on-the-level.)
One block of potentially spurious downvoting occurred approximately one week ago, but then karma patterns returned to expected levels. I consider this block dubious, because it reasonably matches what I'd expect to see if someone noticed several of my posts together and disagreed with all of them, and did not match the usual pattern of starting with the earliest or latest post that I had made and downvoting everything (it downvoted all posts in a few threads, but not in other threads), so I'm just adding for completeness.
Spurious, indiscriminate downvoting started up again approximately half an hour ago on Sunday (12/1/2013), around noon MDT.
Edit: And now on Tuesday, 12/3/2013, at 10 AM, I'm watching my karma go down again... about 30 points so far.
Edit: And now on Saturday, 12/14/2013, at 2 PM, I'm watching my karma go down again... about 15 points so far, at a rate of about 1-2 points per second.
On #1: I think calling something "middle-school-level" is, when applied to something done by intelligent adults, itself a term of contempt. I would not use that term to describe something I thought worth caring about. (I remark for clarity that it wasn't I who used the term to describe concerns about karma.)
On #2: I agree that an ideal reasoner could have both those properties but am fairly sure that very few real human beings (even in the rather unusual LW population) do, whence my remark about halfway-normal human beings.
On #3: "Senseless" is too strong but if there are rogue agents engaging in such capricious acts then the value of karma score as an indication of the worth of someone's contributions is reduced. More noise, less SNR. So if you find karma useful as a rough guide to a person's level of useful contribution, you should be able at having noise added to it. (You might of course be glad of the noise for other reasons, e.g. if you wanted a particular category of person to be intimidated.)
On #3: Fair enough... I agree that if I use the signal, I should prefer that the noise in that signal be lower, all else being equal. So, yes, in that sense I should care. Agreed.
On #2: Yeah, that's why I agreed that it might be true.
On #1:We may just have to agree to disagree on this one, as I'm too infuriated by what you're saying to engage with it reasonably.