A young company needs a way into a market. The wedge is the smallest problem painful enough for a customer to change behaviour now, and narrow enough for a small team to solve with unusual depth.
The danger begins when an entry point becomes an identity. The first customer asks for a faster version, the roadmap fills with refinements, and a company that began with a view of the system becomes a competent tool for one corner of it.
A good wedge carries evidence of the larger company inside it. Solving it should create data, trust, distribution, or a position that makes the next problem easier to reach. If the only path outward is a slide about adjacent markets, the wedge is probably a cul-de-sac.
Start narrow because attention is scarce and trust is earned specifically. Keep the thesis wide because the first product is a sequence, not a destiny. The wedge opens the door. The company is what becomes possible once you are through it.