Better be late than never!!
I do agree that AMD did poorly regarding CPU support. All along, CPU support has nothing to do with chipset. Today's chipsets are mianly just providing connectivity options like SATA, extra PCIE, USB etc....
All your CPU support, overclocking, PBO etc etc comes from the CPU and BIOS directly. Even your 20 usuable PCIE 4.0 lanes are from the CPU (nothing to do with chipset). I would say at least some of the x370/x470/B350/B450 boards are designed to conform with PCIE 4.0 standards but AMD do not allow manufacturers to enable it due to marketing reason. Doing so will greatly affect their x570/B550 sales.
AMD ditch x370/B350 after a year and introduce "new" x470/B450 that has nothing to offer over older chipsets. IF you are talking about extra PBO, better memory OC etc, they are from the CPU and BIOS and to an extent board design (trace length/path, power), but not chipset. Barely a year later, they ditch x470 by introducing x570 chipset that "supports" PCIE 4.0. B550 came later because x570 was too expensive for many pple.
We used to think that AMD was the underdog. They brough us affordable CPUs (Intel was the real devil). But no, AMD is just another devil. I am glad Intel is now competitve again so they are keeping AMD in check. I used to be a big big AMD supporter but now I only support my wallet. Screw these companies.