"A machine that can provide only a few cores, almost no cache, and 64 GiB of non-ECC DRAM is just an ordinary PC, at best."
No, it's not. I don't know where you think PC ends, but that's not ordinary for the range. You don't normally get 64 GB RAM in a PC, either a business-oriented or home-oriented one. Eight cores at 5.2 GHz likewise is not an ordinary spec. Compared to a server, of course, it's very different. Also compared to the top of AMD's range with their superiority in multicore chips. Still, that's well above average for a machine a single person is using.
"Yeah that's not helping any. Intel aren't making competitive products these days. If you want a quiet small form factor machine, you want something like a Raspberry Pi 4 or if you insist on x86 you're going to be looking at specialty low-power parts (see FitPC for examples)."
This is getting ridiculous. Intel's competitiveness versus AMD is less than it's been for a long time, but they have plenty of low-power chips. Especially if you're considering the Raspberry Pi 4 as a comparison. The BCM2711 isn't slow compared to those that came before, but many low-end Intel chips easily outclass it. In addition, if you're buying a low-end computer, the ones using Intel's chips are likely to have better thermal performance than a Pi, which needs assistance with cooling due to the size constraints and power of the new cores. AMD is getting some interesting chips in this range too, but this is an area where Intel has been competitive with it while the high end has gone to AMD; in the past few years, AMD has had few chips that could operate in the low power limit and still work well.
"These days my minimum threshold for "workstation" is 16 cores, 64 MiB of cache, 256 GiB of ECC DDR4, and 3x 4K60 DisplayPorts. You're not going to get that from anything in this line."
You're right that this line won't do it, but mostly I have to ask why you need that. Most of the time, "workstation" means single user. What are you doing that requires 256 GB of memory, and whatever it is, you know that few other people are doing that and many who are are using a server to help with the heavy lifting.