I guess they forgot to explain that while it's not bots that do it, there's a feature in reddit code itself makes it look to many people that such bots exist: http://www.reddit.com/r/WTF/comments/eaqnf/pardon_me_but_500...
I've linked that so many times in threads about tragic events or sensitive questions where people even a single downvote personally (ie. it can happen with very small scores but high activity)
For example, years ago when reddit was new I used to post actual articles and consistently make the front page with them. But one day all my submissions suddenly started getting downvoted, many almost immediately after posting as if someone or something was constantly monitoring the new submissions page, killing any chances of developing the critical mass they used to get or of making it to the front page.
The nature of my postings hadn't changed at all, but the nature of reddit's voting behavior had, and not gradually but unnaturally abruptly, hence the suspicion. Whether it was a human voting ring like was exposed at Digg a while back, or actual bots, or just some no-life basement dwellers with nothing better to do than game reddit all day, I have no idea. I eventually abandoned that account, and now only post comments and the occasional question thread to smaller subreddits.
Of course one person's anecdotal experience is hardly evidence, much less proof, but suspicious nonetheless. When the reddit guys visited you and denied there were any bots, did they explain how they knew this? User agent info, statistical behavioral analysis, etc? I'd be really curious how they go about testing that hypothesis against their massive amount of data.
I'm glad they have that choice, and the ability to share their story. In perspective there are many people in this world who die "unknown" - PBS airs the pictures weekly of teenage American soldiers who died in Iraq or Afghanistan - then there are those who were killed while trying to non-violently protest their unjust government (China, Iran, etc.) - then there are those who are too young to speak yet who are dying of starvation in certain parts of the world today.
Not trying to judge or weigh who is more worthy of a voice, I can only say it's good this one person got to be heard.