I use share buttons all the time on social platforms, and apps like Amazon that don't have any other way of deep linking.
Lot's of people use apps that don't expose a link, share buttons are great and even better when they use standards like your OS's share functionality.
I have a hunch that amazon links do track somehow based on timing. Does anybody do that?
There are so many products on amazon sharing a link to one specific product and having someone else open it shortly after sounds like a high enough confidence.
Again just a hunch.
That is one of the reasons any publisher wants you to install yet another app in your phone. Be it fb, ig, goog, tk... Edit: Reddit :/
The article is discussing "share on [Facebook,Twitter,etc...]" type buttons on websites, not share via [OS functionality or other native app] buttons inside native apps.
That said, I'm curious as to why someone with enough technical sophistication to be posting on HN browses Amazon with a native mobile app instead of a web browser.