To be an entrepreneur, you need to be a tenacious individual with a solid vision and a feasible plan to back it up. Even so, without a plan that you can put into terms that most people can understand and accept as being true, you are not going to get much traction. Your idea needs to be sensible enough that the people who read it can make the necessary mental leap from what currently exists to what can and hopefully will be.
Your plan also needs to have lots of references to be convincing. If you make a lot of statements without support, your business plan will not be credible. Your plans need to have documentation proving that you have found some semblance of a way to make them work. A business plan must be informed with research. Information can come from numerous sources, but they must be verifiable and bear scrutiny.
Naturally, plans are going to change. Your documentation also needs to account for contingencies, even ones that are distasteful, such as failure. How long can your proposed organization operate if you fail to turn a consistent profit during the early days? Sometimes an idea is unworkable not because it won't work but because it can't draw the amount of revenue necessary to support itself during the early, uncertain times.