I actually see this from some manufacturers though. A lot say somewhere something like "if you have an issue with this product, DO NOT RETURN TO THE STORE...contact us."
The products I see with a plea like this tend to be difficult to set up or use for some reason or other. I always assumed that they have a higher than usual return rate and are trying to reduce that by asking people to call them for support.
Also, I imagine the number of returns a product gets factors into whether stores want to carry it, so reducing that return rate can be important.
Even if the manufacturer refunds/replaces the item, I can see it being better for the manufacturer in some instances. If they are relying on store prominence instead of brand recognition, it's very important that stores want to actually carry those items, and low overhead return could factor into that.
This is a different case -- usually in this, it not that the retailer would not accept the item back; it is the manufacturer trying to prevent you from asking the store to take it back, as the store would then charge the expenses to the manufacturer.
If the manufacturer thinks a customer are missing some parts (for whatever reason, even if they broke them yourself) they will ship extra parts to avoid dealing with the store.
