i.e. don't make jokes.
I've wondered about this because I've done the same thing and gotten downvoted. There's nothing about not making jokes in the guidelines. Personally I like a little humor mixed with my HN.
Is there some unspoken guideline that HN is supposed to be humorless?
And on a semi-serious note, isn't mildly interesting that one of the most common cultural myths (vampires) may have some scientific validity?
HN isn't against humor per se. Personally, when I read Reddit, I'm in awe of how good the best jokes are. The problem is that you can't have everything; with a culture of humor comes a flood of lame humor. HN's tradeoff is to optimize for signal-noise ratio, so that stuff tends to get hammered.
There are other places to get lots of internet humor. HN is never going to be one of those, not because people don't like to laugh, but because the signal/noise problem is hard.
That's really all I was commenting on. I could have spelled it out like you did, but clearly my tone was not to some people's liking.