Let me phrase it differently.
When people give Apple Music a cut of their song sales, or when people give Apple a cut of their iOS in game spending, it is not called advertisement.
When you pay to tell someone who doesn't want to hear it about your product, thats advertisement.
The smart play here is the platform play. Clicking on a link and leaving the chat is the opposite of the intent and purpose of the chat. It makes sense for search because going to another website is the point. For search it is the correct business model, but for chat it is not. The chat is the platform. Leaving it breaks all the advantages.