Note that basic and text links to other notes are suppressed on export if the destination note is not exported as a stand-alone page, e.g. the destination is only exported as part of the inline body text of another note.
It might be assumed the 'parent' page of the included content would inherit the inbound link but it does not. The latter might seem a bit of a blunt cut-off of functionality but complex pages using a lot of includes (such as some blogs) make upward inheritance of link destinations less simple than it might appear.
So, if your document is to be exported to a format like HTML and has rich cross linking, this issue re includes can be an important fact to consider when designing the templates and how/where content is stored. To preserve cross-linking you will generally need to use 1 note per exported page and ensure you give good navigation links to the site.