NAS seems to cost about the same price as a cheap desktop.
On the one hand the NAS has a dedicated Linux distro, but I could put OpenNAS, FreeNAS, etc, on a desktop PC.
If I go wth a desktop and network sharing on the drives, I can still use the "server" as a normal PC.
So - for home use, not business - why would I want to buy a NAS?
[Update (after the question was put on hold]
I agree that many of the comments are opinion based - and they are not helping me. Are there any technical reason, one way or another? Price may be used as an argument.
Btw in my case, the NAS/server would be used primarily as backup for the other PCs on the LAN. If I go for NAS, it won't be a major pain that I can't use it as a PC. With a server, I might do once a month, if even that often.
@holders - is that a good enough rewording, or can I improve it? I would be happy for one of you to edit the question, if you think that it can be asked without being opinion based. I really would like to hear a compelling case.