So that the product exists. Especially when talking about Dell. Lets say Dell wants to offer a Ryzen 7 Optiplex to businesses. There is demand for it. More demand then there would be for a similar Precision due to Intel only offering a 6c CPU in its desktop offering. Problem is designing and qualifying a new motherboard and system configuration is expensive. With the Volume of Ryzen R7 they would sell it might cost as much as a base Precision. Dell doesn't want to do that. So they offer the an R5 and that undercuts for the most part both the i5 and i7 but because the volume on that would actually be less because it isn't as competitive they still aren't dealing with a volume that would allow the platform to be price competitive. So the next step is to offer the R3, it's competitive with the i3, but it requires a GPU, that increases costs but honestly the volume is going be a lot higher than the R7 and R5 because you are getting down to impulse purchasing level and this is always going to be a sweet spot, this is also starting to get down into the uneducated buyers level. To cap that off you offer the Lowest end APU (let's call it the 2300G) because that would be AMD's Sub $100 APU and would bring the system down Black Friday awesome deal pricing. Being there is a big key and the last two steps become volume sellers even if they aren't competitive. Now the major market points are hit, from there Dell can offer all the mid steps they want because why not?
Then to add onto that Dell wants to offer an AIO. There Choices are GT2 based Core i systems, spending out the but to get Iris CPU's, or using GT2 systems with a mobile MX150. Or they can go with AMD offer varying levels of GPU power and CPU in their APU's which would be close to the MX150, use less power and generally be comparable to the Core i products they would use CPU wise. Now since they are offering Desktops with the APU's they already have a CPU supply of the APU's. Boom another Design win for AMD.
Dell offers these systems once they can be priced competitively because it gives them the flexibility to offer everything customers might want. It's why they were dying inside when Intel was paying them upwards of nearly a billion a quarter to use Intel only on their systems. They could only take so much of not offering what customers may want before they gave in no matter what Intel was paying them. For AMD, Dell selling their product is a huge win. Even if the volume doesn't come close to Intel (because really we need to stop thinking AMD has to beat Intel to be successful), just having them offer it is going to be a huge boost in volume of their sales.
