I don’t use them for “things.” I use them as desktops, and have been doing so for quite some while - since about the Pi3 era. Right now, two of the desktops in my office (the always on IRC/Element/terminal/light web box and my “main desktop” position, which is used for web/dev/music/admin/etc) are both ODroid N2+ boards - hex core with 4GB RAM and eMMC. The always-on box has gone from a Pi3, to a Jetson Nano, to a Pi4, to the N2+, gaining useful capabilities with most of the steps (the 8GB Pi4 was probably the high water mark just because it had more RAM, but I also sold that for the cost of two of the N2+ boards, and the USB SSD was a bit erratic at times).
So the short answer is that I’m benchmarking, and using, them as “proper computers.” The Rock5 is about 27% the kernel build performance (for a full aarch64 Linux kernel) of a desktop with an AMD 5700X, and not too much worse percentage-wise against one of my 3900X compute boxes.
Regarding building stuff yourself, the point of that is that the mass produced overseas crap is either selling your data or impossible to update/hack, whereas something you build yourself should be a lot better behaved.
As for how they fit in the “critical of modern consumer tech” view, they’re cheap and increasingly capable Linux machines that, more and more, are entirely usable as a full on computing device for more and more people - and as the capabilities improve, they should, with some work, be able to properly run more siloed OSes like Qubes. The Rock5B is the first ARM SBC that has the chops to usefully run Qubes, though it’s not ported to ARM yet. 4+4 big.LITTLE (with quite capable cores), 16GB RAM, and NVMe - that’s on a par with my Qubes laptop I have at the moment (2C/4T 5th gen i7, 16GB RAM, NVMe), which is a genuine daily driver machine for me. Yes, it’s Intel - Qubes and AMD have problems with suspend, among other things.
SBCs as desktops are inexpensive, but also quite hostile to the Wintel world, which I’m perfectly in support of.
I do plan to finish out some reviews, sell some of mine off, and focus more wood behind the Rock5B, though. Assuming I can get a clean framebuffer mode out of it - GPU drivers are currently quite hairy.