It's not a great methodology for Hacker News-esque services since there is no central editing authority for submission titles, so comparisons are apples-to-oranges.
Yes, I agree with what some of you are saying on here. This type of analysis may not apply in all cases. However, if you read the post more closely, you will get a much better picture of each community and will get ideas on how to use this type of analysis for your own blogs or content marketing strategies.
You will be able to learn what the audience cares about, how marketing communities such as GrowthHackers and Inbound differ. And this type of information can help you create even better articles in the future and shed some light on the type of posts that can do well.