It covers the subject broadly and hands off to the cluster for depth. On this site the pricing page is the pillar for everything about website cost, and the free tools index is the pillar for the tools.
A pillar earns its position by being the page a reader would bookmark and the page other sites link to. It should be the best page on its subject on the site, not a table of contents.
Its job is to convert as well as to rank, so it carries the price, the proof and the next step, not only the overview.