Ask HN: Why do people complain when blogs submit referral links.

I have seen multiple instances where people complain when they post a tutorial or a reading list and point to amazon or other shopping sites. And people get a lot fussy when the links have referral links in them. What is wrong in the blog author getting some money when apparently you are not losing any. In fact you are gaining some knowledge. This is a win-win situation. I am pointing you to the correct resource and cashing in on the fact that I pointed it to you. Isnt a search engine or some discovery place you use doing the same thing?