The problem
Product strategy is the hardest thing to document. It's not a list of features. It's a set of bets about the market, the user, and your differentiation — and those bets are best articulated in a room, standing at a whiteboard, arguing with smart people until the logic holds.
What comes out of that session is usually a whiteboard full of boxes, arrows, segments, and a few key phrases that the team finally agreed on. Then someone tries to write 'the strategy doc' from memory and a phone photo, and it loses the logic. The document shows the conclusions without the reasoning. Two months later, the team is debating a roadmap decision and nobody can remember why they made the strategic bet they made.
The whiteboard is the reasoning. If you can preserve it faithfully, you preserve the 'why' behind every downstream decision.