Contacting a sales department at their provided address for that purpose is responding to a request for you to do so. This is nothing at all like taking money to propagandize people.

Putting a product at a prominent part of your store because you think it's a good purchase for customers is also completely different from accepting money from a manufacturer to place it prominently.

Going to an event where everyone specifically went to meet and exchange information about what people in their industry are doing is also again entirely unlike paid promotion.

Right direct sales is not advertising. The rest still is.

You're missing a step though. There is no consumer pull for new products so there is no reason for stores to bother with them even if the owner thinks it's a great idea. The demand isn't there

They have a similar reason that the product developer had to make it: they have customer empathy, can identify a good product that satisfies a need when they see it, and know how to explain it to customers.