For the early stages, I think you can get away with it, just like you can get away without bringing a professional designer into the picture.
The drawback is that it gets more expensive the longer you wait. The more code from a beginning programmer there is, the more there is to be overhauled, and the more ingrained your seat-of-the-pants interaction design and visual design is, the more challenging it will be for your designer and/or front-end developer to lift out and replace.
Do you overhaul your car or let it be done by a mechanic ? Do you make your own paper ? Do you grow the wood for the trees to build your house ?
Anybody technically can do anything themselves, if there is a skill worth learning then it probably is programming, since it allows you to amplify your ability to get work done in a given amount of time (which usually is your most scarce resource).
But you won't be managing that time effectively if you want to launch a start-up and learn this skill at the same time, then you're probably better of hooking up with a competent coder and letting them lay the bricks in a way that will help your business to succeed.
I'm all for learning new skills, I can weld, but when my life and or my business depends on it I go to a welder.
So if you are not already a competent coder and you have the choice to team up with a coder or to delay the launch of your product by a couple of years to get you up to speed seems like a no brainer to me.
The drawback is that it gets more expensive the longer you wait. The more code from a beginning programmer there is, the more there is to be overhauled, and the more ingrained your seat-of-the-pants interaction design and visual design is, the more challenging it will be for your designer and/or front-end developer to lift out and replace.