[ganeumann]

You're not the target audience (if you're the average HN reader, that is, don't actually know you personally.)

HBR gets a high price for its ads because its audience is older businesspeople (decision makers on high-priced services and products) who consider its content high-worth and authoritative (this attitude rubs off on the ads around the content.) Having a gating ad that scares away people who don't value the content enough to close it probably increases the price per ad more than enough to make up for the slightly decreased viewership of the ad.