@StuM I imagine it might be that cross-site copy paste is the foundation for a global symbol marketplace to go alongside the current template market place. Imagine adding your own built or purchased symbols to a project before even opening the designer. The code to make that happen is probably closely relate if not the same as cs-c+v. This could even be take further to loading global color swatches or a whole style sheet into a project too.
Of course, it could also be something else that will blow our minds. 