That's what my github.com/jwcrawley/uWho project does:
Facial recognition on an old computer with no GPGPU processing.
Now , any of the CVDazzle "exploits" screwing up a LBP cascade on face detection works to subvert my model, as does closing ones eyes. Aside those small details, it was in large a great success for my initial goal.
Now, I'm looking at getting it into a client-server architecture, where I can recognize who lives here, and whom comes over regularly. The idea is that I can have an "aware front door" that can ring a doorbell or send a message (with who: text/picture) if we are away. Even crazier is to allow bidirectional voice to us over a VoIP connection.
I see its purpose in a part of the home IoT infrastructure that isn't like a "internet toilet" kind of uselessness.