The article incorrectly talks about supporting AM4 for five years. The original talk from AMD was that at Ryzen launch in 2017, AMD would support socket AM4 through 2020. This was before Covid-19 caused the chaos and delays in getting new generations out the door. So, in 2020, there was actually a good question, would first generation motherboards support chips released in 2020, or through 2019? Good UNTIL 2020, or through the end of 2020 is really where the question of intent, wording, and mistakes by various press sources have made that a bit vague.
Without a doubt, AMD has supported the socket. The problem is again with the interpretation, can you use your first generation motherboard from 2017 with chips released at the end of 2020? AMD has artificially prevented Zen3 from working on those 300 series chipset boards. Initially, AMD even prevented the 400 series chipset boards from supporting Zen3 but did indicate that 400 series chipset motherboards would get support in February of 2021 or so, which did happen.
Now, if you did follow the supply issues, and how Zen3 was sold out continually for at least six months after the launch of the Ryzen 5000 series processors, AMD preventing upgrades wasn't a horrible idea, just to reduce the demand for those processors. We are also at an interesting point, will Zen4 be fast enough to justify going with an all new motherboard+CPU+RAM, vs. upgrading your CPU on a first generation motherboard that doesn't support PCIe 4.0? I am expecting that Zen4 will be at least 20 percent faster than Zen3+, but $550 for a 5900X, vs. $1500 for a new motherboard+CPU+RAM that will be maybe 40 percent faster than the 5900X plus PCIe 4.0 speeds, SAM support(which many 300 series chipset boards don't support), plus other benefits such as Rage Mode, that's the decision people will need to make.