If they themselves say they discovered a product that they were interested in, how is that not value addition? Value isnt defined in your advertising free ivory tower.

It isn't defined in your ad-filled cesspool, either. I don't see convincing someone to buy something as an absolute positive value. There's nuance. Making someone aware of a product that will genuinely improve their life is great, but most ads in my experience are more like drug pushers.

Ah, yes, because we brilliant hacker news readers know that the average person is too stupid to know what things they should buy or not buy.

That's not my interpretation of that comment. To wit:

There are only a few things you can know about someone clicking 'buy' as the result of an ad:

1. The ad platform booked top-line revenue

2. The seller booked top-line revenue

3. The buyer exchanged money for something they thought was worth it at the time of purchase.

That's it. Even #3 is conjecture, but it's likely enough that I'm willing to run with it for sake of argument.

We do not, and short of asking, can not know if that purchase added value to the buyer's life.