Right- but if it doesn't have a timestamp, then it's difficult to determine whether or not one user downvoted another user many times in a few minutes, which is a more reliable sign of the karmassassination problem than just how many times one user has downvoted another user.
You could go off comment timestamp- "has user X downvoted a contiguous block of comments from user Y, or are there holes (i.e. comments user X did not downvote)?"- but that's less useful, and more likely to catch the false positives of norm-enforcing users downvoting a repeated norm-breaker.
The past 80+ comments from me have all had at least one downvote. There is no reasonable way to interpret this other than as having a stalker.
And the solution to how not to catch false positives is to use some common sense. You're never going to have an automated algorithm that can detect every instance of abuse, but even an instance that is not detectable by automatic means can be detectable if someone with sufficient database access takes a look when it is pointed out to them.
To whoever has for the last several days been downvoting ~10 of my old comments per day:
It is possible that your intention is to discourage me from commenting on Less Wrong.
The actual effect is the reverse. My comments still end up positive on average, and I am therefore motivated to post more of them in order to compensate for the steady karma drain you are causing.
If you are mass-downvoting other people, the effect on some of them is probably the same.
To the LW admins, if any are reading:
Look, can we really not do anything about this behaviour? It's childish and stupid, and it makes the karma system less useful (e.g., for comment-sorting), and it gives bad actors a disproportionate influence on Less Wrong. It seems like there are lots of obvious things that would go some way towards helping, many of which have been discussed in past threads about this.
Failing that, can we at least agree that it's bad behaviour and that it would be good in principle to stop it or make it more visible and/or inconvenient?
Failing that, can we at least have an official statement from an LW administrator that mass-downvoting is not considered an undesirable behaviour here? I really hope this isn't the opinion of the LW admins, but as the topic has been discussed from time to time with never any admin response I've been thinking it increasingly likely that it is. If so, let's at least be honest about it.
To anyone else reading this:
If you should happen to notice that a sizeable fraction of my comments are at -1, this is probably why. (Though of course I may just have posted a bunch of silly things. I expect it happens from time to time.)
My apologies for cluttering up Discussion with this. (But not very many apologies; this sort of mass-downvoting seems to me to be one of the more toxic phenomena on Less Wrong, and I retain some small hope that eventually something may be done about it.)