I'm no startup founder (yet!) but as someone who's worked with a lot of them when I was in law, that is the surest recipe for disaster, because as soon as there is a disagreement between the founders there is no one who can make decisions.

As one of my law profs (who also has tons of business experience) said to me: "If you remember two things from law school, it should be these: never share equity 50-50, and always have a prenup."