It's upto manufacturer to decide, the product can sometimes a major release, or family that comprises of multiple sub models
A real-life example of a product managed by the content library can be the iPhone 14 series, while the device type can be 'mobile' and the models can be iPhone 14, iPhone 14pro and iPhone 14 Pro max
Now each of these iPhone models can have different lifecycle stages and expiry dates depending on its supported features so i believe this can be one way to look at why it simply doesn't inherit based on the product
