Why does the product start with a map?

Because the question that stalls an SEO project is almost never "which keyword do I go after". It's "where am I".

A list of pages can't answer that. A map can: which page receives internal links and which doesn't, which topic has an owner and which is scattered, which corner of the site nobody ever reaches.

Once the terrain is drawn, picking the fight is easy. Before that, picking the fight is a guess.