I use this kind of blackboard system still when I can't avoid globals. The main thing it helps with I find is you still have to know the order of and when your systems are being setup.

Ran into so many bugs from people creating static instance globals and thinking it was good that they didn't have to care when systems were setup.

I hate create on access with a passion. For god sake just new the damn thing at the beginning of main if nowhen else.