> Even gaming is now more reliant on GPU performance (which in principle ought to benefit from the high PCIe bandwidth of server parts)
A gaming GPU doesn't need all of the bandwidth available from a single PCIe x16 slot. Mid-range GPUs and lower don't even have x16 connectivity, because it's not worth the die space to put down more than 8 lanes of PHYs for that level of performance. The extra PCIe connectivity on server platforms could only matter for workloads that can effectively use several GPUs. Gaming isn't that kind of workload; attempts to use two GPUs for gaming proved futile and unsustainable.
That number of threads will hit a bottleneck accessing only through to channels of memory.
I don't understand why you brought up the topic of single-threading in your response to the user, given that processors reached a frequency limit of 4 GHz, and 5 GHz with overclocking, a decade ago. This is why they increased the number of threads, but if they reduce the number of memory channels for consumer/desktop...
You need to re-check your sources. When AMD started doing integrated memory controllers in 2003, they had Socket 754 (single channel / 64-bit wide) for low-end consumer CPUs and Socket 940 (dual channel / 128-bit wide) for server and enthusiast destkop CPUs, but less than a year later they introduced Socket 939 (128-bit) and since then their mainstream desktop CPU sockets have all had a 128-bit wide memory interface. When Intel later also moved their memory controller from the motherboard to the CPU, they also used a 128-bit wide memory bus (starting with LGA 1156 in 2008).
There's never been a desktop CPU socket with a memory bus wider than 128 bits that wasn't a high-end/workstation/server counterpart to a mainstream consumer platform that used only a 128-bit wide memory bus. As far as I can tell, the CPU sockets supporting integrated graphics have all used a 128-bit wide memory bus. Pretty much all of the growth of desktop CPU core counts from dual core up to today's 16+ core parts has been working with the same bus width, and increased DRAM bandwidth to feed those extra cores has been entirely from running at higher speeds over the same number of wires.
What has regressed is that the enthusiast-oriented high-end desktop CPUs derived from server/workstation parts are much more expensive and less frequently updated than they used to be. Intel hasn't done a consumer-branded variant of their workstation CPUs in several generations; they've only been selling those parts under the Xeon branding. AMD's Threadripper line got split into Threadripper and Threadripper PRO, but the non-PRO parts have a higher starting price than early Threadripper generations, and the Zen 3 generation didn't get non-PRO Threadrippers.