it does seem that most homelabs are big server racks with at least two CPUs and like 20 cores in total. I’m not sure if your premise is correct, a lot of hardware discussion I see is people repurposing old desktops/laptops or running with sff/mff pc’s.
Why should I get a homelab instead of a regular NAS? In case you want more than just storage like vpn services, hosting containerized applications, etc.