Earlier quoted context omitted.
Why is it not an example of tacit or autonomous algorithmic collusion? The agents were started with something as task at some point, I presume (if untasked, aren't they just accepting a task?)
What you're suggesting sounds like it's describing subagents. In that architecture they'd have no need of finding/creating external messaging systems since they'd effectively be in direct contact anyway. The whole point of the shared blackboard would presumably be communication across agents or across multiple generations of agents. Not like we have much detail about this stuff (that's the whole problem). But the que…
Given how unexpected and complex behavior can come from simple reward functions and mechanics, not sure there needs to be so much "thought" there.