Your comment makes much more sense if you also want to have a desktop,and only in some network configurations. It's most likely the minority use case, but worth considering if it might fit.

A lot of people just use laptops and tablets / phones with limited storage expansion space at home, and want a dedicated device for a firewall/router anyways (no worries about reboots or other interruptions due to personal work on that computer, etc).

One more powerful computer to use as both NAS and firewall (and for various shared services...) makes a lot of sense much of the time - hence the popularity of proxmox.