By-the-way, if you wonder where the Dictionary comes from I found this in Dictionary > Preferences…
That would appear to rule out any consideration of Royalties — at least for the basic dictionary content.
When I select Dictionary > Prefs > Wikipedia in Sierra I see the text you posted, but with
additional language...
It applies to Wikipedia only.
All other dictionaries have appended text similar to this...
New Oxford American Dictionary
Copyright © 2010, 2016 by Oxford University Press, Inc. All rights reserved.
Royalties most certainly are an issue and have, perhaps (
), influenced content.