For example when the topic was constructible polygon I post a link to https://en.wikipedia.org/wiki/Constructible_polygon then the oneboxing looks nice and very useful.
In above case, the onebox has a lot of value.
However, if the topic was about about something more specific such as Compass and straightedge constructions which requires an anchored link, the adding a link to https://en.wikipedia.org/wiki/Constructible_polygon#Compass_and_straightedge_constructions is much less useful.
Could this be improved somehow?
Ideas:
When # is in the link, ask the user if a onebox should be generated while typing?
Drop the generic image from og:image meta tag?
Add an image form that specific (wiki) chapter contained in the # anchored link, if any?
Add the title of the (wiki) specific chapter instead of the title of the (wiki) page (og:title)?