Which isn't much of a surprise considering what I have observed so far (in trying to purchase a Linux PC). I can't recall ever having seen an OEM offer Linux for more than a sparse subset of their product line, usually mid-tier or low-tier machines.
>A few are still trying.
Which ones? The situation may have changed since I last paid any attention a few years ago.
>The real problems are selling and supporting them.
The MVP here is to merely accept returns for units that turned out to be particularly troublesome; which they usually do (ie: the Samsung UEFI thing from 2013).
A non-Microsoft UEFI key thing might be nice as well, but that's another story.