I think the appeal of the RPi has to do with the amount of online tutorials that beginners can understand, and the experience of assembling something from pieces.
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But if you don't want that, there's no need for "online tutorials for beginners" and that shouldn't be counted as an additional appeal. It's just Windows.
For basic homelab use cases, almost any computer is fine, but for IoT-style stuff especially, a Pi-focused will have a lot more hits, and the tutorials won't apply to any of the mini PCs.
What pieces? RPis are single board computers, no assembly required.
If Intel NUCs were sold without a case/shell, they'd probably be able to appeal more to the same hobby market RPi dominates (although the RPi does still look more aesthetically pleasing)