1. Shipping - The most basic need that a PM satisfies is shipping features. This involves day-to-day tackling of large and small decisions that block the successful release of a new feature.
The Lean Startup model has pretty much become the orthodoxy for launching a new product or company today: build an extremely rough version one, launch it, find some users, and then iterate on the product as quickly as you can (pivoting).
Another one of the biggest benefits of a written PR/FAQ is that it enables the team to truly understand the specific constraints and problems that would prevent a new product idea from being viable and aligning on them.
Ownership: I can give you a problem statement, but you’re the one who determines what your job is. You don’t get driven around by the team; you figure out what the team needs, and you deliver that.