1. Placing an Ad on the page has absolutely nothing to do with selling your data. Just like a magazine decide to place a print ad.
2. Ad can sometimes function as news. New Product launch, marketing notes. etc.
3. Even an internet targeting Ad, which the author is likely referring to, does not necessarily sell your data to advertiser. Your data, however may likely be gathered elsewhere that the Ad company uses for targeting.
4. There is no such thing as double dip when your data isn't even involved. Which means you are only paying once. And not twice.
5. Placing an Ad, an additional revenue generation function on the site is not double dipping. Even if the ad is inside your subscription. You are free to cancel or sue if the subscription originally promised zero ads.
6. The correct amount of ads is when Ad does not feel like an ad. The answer is very likely to be non zero but minimal.
Final Note: I Notice HN has swing back enough to allow decent discussions on these sort of topics. Ads were nearly forbidden to talk about from 2013 - 2023.