This is not a correct comparison. The machines mentioned:
- have significantly higher consumption
- cost at least 3x (300+ $) as an average XU4 (~100$)
- are desktop-sized (the OP made a custom-one; the vast majority of SBC cases are tiny)
The definition of "server" is not the same for everybody.
Home media servers users, like the OP, just need enough power to play/serve media, and they likely don't need any form of redundancy. XU4 is perfectly adequate for that.
There are certainly other more demanding use cases (eg. storage-oriented servers), but that's an entirely different market segment.
A XU4 with PSU, case and 16gb eMMC will cost you $100 yes, but for storage you'll also need an external enclosure. The only (4 port) I found on amazon was $120 (and it has its own power brick)
So the price is very similar, but the former is server hardware that is more robust, powerful, extensible, and the latter is an android dev board with an unknown amount of "assembly required" time.
Can you post a link, before starting a discussion about this? The fact the it's possible to get an item, intended as a once-off offer, hardly makes a general case.
If a user requirer an array of 32 3.5" disks for his home server, then also a MicroServer is not adequate.
If a 2.5" disk is considered adequate for a home server (they have multi-TB size), there are plenty of SBC+2.5" disk enclosures that are significantly smaller than a MicroServer (of course, then one needs to use a specifc SBC model).
I do have a MicroServer-sized machine as well, and the size is definitely not comparable to an SBC+disk enclosure.
Mine is hidden away, so I don't hear the hard drive clicking, and it doesn't have a case at all.