I've found the voting to be a great measure of what's hilarious. Whereas comments that are only moderately funny or diverge into off-topic are usually heavily downvoted. So, I think the threshold is just very high for jokes.
This post reminds me that I need to have more diversity in my life and reading material. All of these ideas struck me as good, and then I realized they are all basically targeted at people like me because that's the type of people who created this list.