Obviously the importance of it depends on the product, and some things don't do it at all, but there is the consideration that although two products came from the same line, they were branded according to how well they passed QA.

Sometimes they keep the same overall brand (see: Intel and AMD disabling defective cores) and sometimes nobody even pretends that the product you are buying is not the result of failed QA for another product (bags of broken pretzel bits), but between those you get a fuzzier line. I have heard that consumer batteries do this for example: the weird-brand batteries that come in your remote control from the factory are probably rebranded batteries from a company you have heard of.