(I'm behind both)
This is true only of American dating sites. A number of Indian dating sites are based on that exact model.
I guess the lesson to take from that is this: if your expectations are low enough, and social pressures not to quit are strong enough, any reasonable pairing can be made to work.
To me, first and foremost, the fact that you don't have any out of pocket expenses is a good thing, it eliminates one barrier to entry. Virtual companies achieve that. In comparison, joining a "real" incorporated startup as co-founder, the first thing you do is split the legal costs and buy your shares. So right there, a few thousand dollars before you even know if you should work together. And there is no "undo" button, unlike virtual companies.
That's also why in the co-founders meetup I ask the presenters to not only present their business, but reveal a bit of their own personality. I believe that compatibility as co-founders comes equally from being passionate about the same things but also being compatible personality-wise (read this http://blog.fairsoftware.net/2009/11/19/first-co-founders-me... for more on the topic).