No, this behavior devalues the community as a whole. Karma works as a democratic filter, and abuse of karma allows control over the community which is out of line of stated objectives. These are crimes against everyone who is participating in good faith, not just you.
You're only moral obligation is to be as certain as you can be of the guilt of the accused.
If the LW community cares about this issue, then they should just petition an admin to check who is doing the downvoting. There is a log of "liked" and "disliked" which is available. They could even set "dislikes" to public. Even in the event that the retributive downvoter uses a puppet account to downvote, we can still automatically prevent accounts from selectively downvoting all a users posts.
There's absolutely no reason to guess at naming specific people and starting a witch hunt. Since the person didn't necessarily use a ...
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.