I'm not informed enough to have an opinion on Dan as a person or on HubSpot, but this is the third article I've seen posted to HN that all pretty much say the s

I'm not informed enough to have an opinion on Dan as a person or on HubSpot, but this is the third article I've seen posted to HN that all pretty much say the same thing, and are all obvious attempts to sell his book. Why do these articles keep getting voted up?