It might make more sense to say a startup without revenue or a monitization plan is just some code. While likely unintentional I think "business plan" trips people up. The idea should def cover how the startup will get users and make money.
When the technical person creates the working product, they have delivered on their side of the bargain. I think the problem is that many non-technical founders think they have made the equivalent contribution by having "a plan". They haven't. They will have made the equivalent contribution when the execute the plan and make money.