Good question! One minor nag (isn't there always one?) - I don't like the wording "System objects such as sys.objects are physically persisted in the Resource database" (and yes, I know that similar wording is used in BOL). This suggests to me that the result of "select * from sys.objects" is persisted (as the same term is used in documentation about indexed views, aka persisted views - where that is exactly what happens).

Reality is that metadata about user objects (which is what you see when you query sys.objects) is stored in hidden tables in user databases; sys.objects is not a system table but a system VIEW, and the source code of that views (the query on the hidden actual system tables) is what's stored in the resource database.