You can actually do some crazy things with a homelab. I have a store-and-forward network joining roadwarrior machines to machines on my home network organized in a hub-spoke-ish model. It lets me access media from my home network even when I'm on some super oversubscribed AP (at 256 KB/s) at some crappy hotel with awful firewall rules (like only letting TCP traffic on 80 and 443 out) without opening any security holes on the network itself. I was able to experiment and deploy the network using the machines in my homelab.
As far as the name, I think it comes from the term "networking lab" that netops actually use to trial out network topologies before deploying them in the field. It's a home networking lab, that's all.