It's good to know that the person posting the link has a financial stake in it. Depending on the context this can mean a lot - like a review or recommendation.

Except it's Amazon. I could understand that position if it was a Dell affiliate link. But Amazon sells so many brands of monitors, any of which could carry the same affiliate code, that I don't see how that matters.

Just like the FTC, I do not care about the existence of the affiliate link being on HN, but only the disclosure. It makes for a fair(er) market.

I pointed it out, and I don't really care exactly--I just think it's common courtesy for the person to disclose it.

He didn't, so I did for him.

It's a conflict of interest. People are more likely to share links that get them the most affiliate $$$.