> Linking to company websites so people looking to buy stuff that company makes can find it is a scam, because company websites are biased in favour of that company

This isn't a faithful interpretation of the argument. Most people don't use Google to look for things to buy. They use it to find accurate information.

I wasn't even talking about paid links specifically. It's advertising in general that's the problem. Call me a child all you want, I don't care. The simple fact remains that they have an inherent conflict of interest. It's not an absurd argument at all. People who want to sell you something have every incentive to distort the truth and only fools believe them.