What does a stay-at-home partner without kids, actually contribute?

Im basing this on the traditional male-female setup: husband takes care of bills, and wife takes care of the house. Im looking toward something like this, but without kids in the mix, being that I'm child free. Without the kids there, I dont really understand the need for a partner that stays home all day; maybe im underestimating the effort that goes into domestic work. Everything that they do, I can just do myself. Id at least like them to have a part time job. Is there something I'm missing about this scenario? Any examples of this setup?