I’ve been using the site for a while now and wasn’t aware of that rule for Show HN. It’s clearly articulated, but I could see someone that didn’t RTFM just using it to amplify their post of something cool.
I didn't know that either, so I posted a couple of Show HNs that is not mine before.
I have read the FAQ and guidelines before, but never stumbled across this page.
Easy misunderstanding. Yet assuming you didn't know this, it would logically raise a question as to why all posts featuring some form of product or service were not Show HN then.
It would be also a good idea to promote that page a little more. I have gone through the guidelines and FAQ multiple times checking for stuff, but never saw a link to the said page.
I really don't have the resources for the level of conspiracy you are implying :)