Create a new page during linking, if it doesn't exist.
When creating a link to another page, most apps, like Roam, Notion, etc... allow one to create a new page if it does not exist.
Some apps, however, only allow linking to an already-existing page.
There is a third category, too. (I think Slatr does this) where you can only create a subpage, but can't create a page in a different / global scope.
Ideally, when linking to a non-existent page, you can create the page, and place it into any context. Otherwise knowledge-graph creation gets really clunky!