I want a type of desktop PC (and motherboard) that's generally skipped
By now, the desktop x86 PC market has segmented itself into a number of categories. There are machines, CPUs, and motherboards that are basic machines with limited features and made to be quite inexpensive, 'business' machines that don't need very much but are more than the very basics, machines for gaming enthusiasts, and HEDT ('High End Desktop') workstations that are aimed at people building high powered machines. Typical examples of what are in these categories are in Anandtech's Best CPUs for Workstations and Best CPUs for Gaming; in Intel motherboard chipsets there is the H series, the B series, and the Z series (sometimes among others). Unfortunately for me, my interests in machines fall into an intermediate category that doesn't generally exist, which I will call a sysadmin workstation.
Every system administrator probably has a somewhat different view of what they want in their desktop. My image of a sysadmin workstation is exemplified by my current home machine; it has a fast (Intel) CPU, it takes a fair amount of RAM that can run at faster than completely stock speeds, it has at least M.2 slots (both of which run at x4) and four SATA ports, and it can drive at least one 4K display through onboard graphics. Unlike a gaming machine, I want to use integrated graphics (they're quieter, less clutter, cheaper, and generally better supported on Linux) instead of a GPU. Unlike a HEDT workstation, I don't want a fire-breathing CPU with its increased cost and cooling requirements (and I also don't want one or more GPUs for GPU computation). And I want more storage (especially M.2) than basic home or business desktops usually provide.
(I might change my views on GPUs if Intel starts making discreet GPUs that are well supported under Linux, drive two 4K displays at 60 Hz or better, and don't require lots of cooling.)
It's possible to put together a sysadmin workstation, of course; I did it for my current home machine and my current (AMD based) work machine, although the latter has to use a GPU. But it generally involves buying more than you need and picking through specifications to narrow in on the bits you care about, and the motherboard support for integrated graphics is often somewhat limited. People who buy motherboards with lots of features and high specification generally use GPUs, so there are a fair number of otherwise suitable motherboards that just don't support onboard graphics. I'm also lucky in that Intel still provides versions of their higher end desktop CPUs with onboard graphics. AMD has historically restricted onboard graphics to lower end models; if you wanted a reasonably powerful Ryzen, you were stuck getting a GPU.
(As far as Intel versus Ryzen goes, I still don't trust AMD. My Intel home machine still has its problem of hanging when the temperature drops too low, but that's a narrow issue that's probably a motherboard fault. The coming of winter with another go-around of this issue is one reason I'm thinking about motherboards and desktops and so on again.)