As someone who has purchased a half dozen SBCs over the years but who has also switched to mini PCs the other thing that you start to miss is having a real BIOS so you can install a vanilla operating system. With the SBCs, there is often a single Linux distro that is supported, and which rapidly stops getting updated. Even using stuff like Armbian, it's challenging to use an SBC that is more than a couple years old, and I've had bad experiences where the NIC stops working after a software update.