It's about incentivizing sites to do what the user wants them to do. As a user, 99% of the time I am not out to buy something, so all sites that do try to sell

It's about incentivizing sites to do what the user wants them to do. As a user, 99% of the time I am not out to buy something, so all sites that do try to sell me something are just wasting both my time and their server resources. This isn't a complete blanket ban on ads or the commercial web. If there isn't a profitable way to run a website that provides the content matching the search query, the ad-infested website will still come up first. But now, a hobbyist, non-profit or even commercial enterprise that doesn't directly sell to you has a chance to outrank the ad-infested garbage.