The architecture here is similar to old PCs (roughly before 2010) that had integrated graphics in the northbridge. The memory controller also resides in the northbridge. The CPU communicates with the northbridge through the front-side bus. Incidentally the northbridge also used to be responsible for high-speed I/O such as PCIe, so even if you had a discrete GPU it would not be connected directly to the CPU.

Over time CPUs have integrated all those features on-die, resulting in today's SoC-like processors where the "chipset" is merely an I/O expander connected over a PCIe-like link.