Earlier quoted context omitted.
Note: the I/O chip on AMD Zen 2 / Zen 3 is a 14nm GloFo chip. Only the CPU-cores ("Zepplin" maybe, or whatever they call them now) are 7nm TSMC. So AMD's strategy also leads to lower fabrication costs: because they can make a far cheaper 14nm chip to handle the slower portions of I/O (talking to RAM, or PCIe), while the expensive 7nm parts of TSMC are used only for the cores / L1 cache / L2 cache / L3 cache.
Small nitpick: if I remeber correctly, AMD now uses 12nm process from GloFo now instead of 14nm (due to PCIe 4 requirements).
Zen 2 has PCIe 4, so you could very well be correct.