I'm sorry you got some downvotes, because what you're asking about is interesting: Am I merely saying "Don't post stuff I don't like?"
I don't think that I'm asking people not to post stuff I don't like. For one think I like some of the stuff I'm asking people not to post. Yes, I like lame jokes. I don't think "lame" and "dislike" are strongly correlated. If people upvote something, it could be popular yet lame in some way. And if people don't want to see it on HN, they might still like it.
Here's an example. I like puns. I especially like spur of the moment puns. But quite honestly, puns are usually a fairly low form of joke. They rarely have any kind of serious insight into the human condition. I don't mull over puns and repeat them as anecdotes years later.
So, I can tell you that something to do with a pun would be (a) enjoyable to me, but (b) lame, therefore (c) I wouldn't submit it to HN, I'd probably tweet it.
We aren't really discussing puns, but i use them to try to illustrate the idea that there are things that I might like or you might like that are funny and fun and worth repeating, but they don't necessarily belong on HN. I don't blame you for liking such things, just as I'm not ashamed of enjoying a pun.
So perhaps "lame" is a bad word, because it is pejorative. Perhaps the suggestion might be "Don't post April Fool stories that lack any real insight or clever prank that takes you in." Lame might be the wrong word.
But I think the idea is worth discussion, the question of whether there are things someone likes that shouldn't be on HN. I agree that the rule "Don't post stuff I don't like" is wrong, as is any proxy for that idea.
And thank you for raising an interesting question.