Most strategy documents are a list of everything a company would like to be true. Strategy is the opposite of that. It's a small number of choices, made on purpose, with the alternatives visibly crossed out.
Who are we for, and who are we not for. What problem are we solving, and which one are we walking away from. Where does the advantage actually come from, and is it real or is it just something we've all agreed to say?
What changes: the roadmap gets shorter, the pitch gets sharper, and arguments that used to run for months get settled in an afternoon, because at last there's something to settle them against.