> Typically you are not forced to sell your product on just one store, with some exceptions, of course.

This is absolutely not true at all, exclusivity agreements are incredibly widespread in supply chains.

https://www.kevingrier.com/uploads/userfiles/files/opinion-p...

> Both retailers and manufacturers assert that over the past decade this practice has increased materially. In some retail outlets or corporations, the activity is now found in virtually every category. Based on reliable industry benchmarks from the late 1990's it is likely that as of 2001, at least half of major Canadian manufacturers are involved in some form of exclusivity arrangement with Canadian distributors.

“With some exceptions” doing some heavy lifting I guess, considering we’re talking about basically whole industries and product sectors.