Here are some examples of where an RPi outshines a mini-PC (though one can still achieve the same results, just putting the box outside the box):
Coffee table Digital Touch map.
Weather Station powered by a solar panel and a LiPo battery.
ADSB receiver also powered by solar and a battery.
Arcade Cabinet that sits on a bar top with a bill reader.
Mini JukeBox at the local hacker space.
Sailing autopilot using NMEA2000 connectors.
Wearables.
Playing with high density distributed computing. (More than 5 machines)
Where the mini pc really shines is:
Storage. (NAS included)
Media PC (TV sold separately)
Gaming Console
Personal Cloud (docker + nfs + caddy + <insert personalized preferences>)
General Autopilot (sensors that need GPU support).
You have left over old PCs and don’t want to open your wallet…
I was commenting in the context of why people choose them for servers but I recognize that I did not make that clear.
Similar to anything running in SMM (System Management Mode) on X86/AMD64 since the times of the 386SL. Be it BIOS, APM, ACPI, UEFI, or whatever.
I repeat: "It's just an illoooshn..." (There is now raw iron/silicon for consumers)
Thing is, I was aiming at servers. I've read many HN comments where people adore a Pi for some reason that I just can't see; they have to install custom kernels, get Pi hats, do some extra cabling, 3D-print cases, mount small (or big) fans, and all that.
And don't get me wrong, I love tinkering myself but after reading people's experiences for a while I just thought to myself "Why all this trouble? Get a $250 - $400 mini PC off of Amazon / eBay / AliExpress and put a 2-4 TB NVMe SSD and you have something 20x more powerful and with 100x the storage space".
Again, I love me some tinkering. But nowadays I want to get something out of it in the end. Like the mini PC I bought that I want to dedicate only to a PiHole even if it's a 50x overkill for it. Might add some firewalling / VLAN management capabilities to it down the line.
So yep, for education RPi and Arduino (+ its derivatives) seem mostly unbeaten.