Neighbourhoods have some interesting properties, growing by both referencing pages on other sites and forking content.
However, both these methods of growth only happen when you visit a page that either contains a reference to, or has been been forked from, another site.
So, if say Ward was to fork this page and add some extra content. If you navigated here via the Thoughts on Federated Wiki page you would see that he had a newer version of this page. If to got to this page via another route which didn't add Ward's site to the neighbourhood, say Recent Changes, then you would not see that he had a newer version.
Simply having the references on the Welcome Visitors is not a complete solution, as it is possible to link directly to a page.
Simply having a reference on Welcome Visitors may prematurely enlarge the neighborhood when the reader intends to work in a distinctly different region of the federation.
The default Welcome Visitors page was a one time concocted such that it expanded the neighborhood to include help pages from fed.wiki.org. A less intrusive solution has been to include a copy of How To Wiki in the standard plugin pages.
A good approach is to define a page of related sites, give it a meaningful name, and link it someplace close to Welcome Visitors.