Mental note: Don't take on a "business" partner.

Why not? I don't think Steve would say that it was a mistake to partner with Alexis. There's a lot more to a startup than just the tech stuff.

I think a better lesson to learn from Reddit might be "Don't take a technical partner who decides he wants to be a sociologist 3 months in."

I agree. Take on a "mascot artist" partner instead.