The only reason I can see is "I have one that I don't use". Because otherwise...
Idle power isn't all that much better than a low power Intel N100 or something similar. And it's all downhill from there. Network transfer speeds and disk transfers will all be kneecapped by the (lack of) available PCIe lanes. Available RAM or CPU speeds are even worse...
> I've found numerous times, running modern applications on slower hardware is an excellent way to expose little configuration flaws and misconceptions that lead to learning how to run the applications much better on more capable machines.
It's less about the why, and more about the 'why not?' :)
I explicitly don't recommend running TrueNAS on a Pi currently, at the end (though I don't see a problem with anyone doing it for the fun, or if they need an absolutely tiny build and want to try Arm):
> Because of the current UEFI limitations, I would still recommend running TrueNAS on higher-end Arm hardware (like Ampere servers).
[1] https://www.jeffgeerling.com/blog/2024/radxas-sata-hat-makes...
imo, if the software doesn't work without issue on my Pi, it isn't good enough for prod.