In a new post on his blog Adam Wathan explains his thinking on the meaning of having a method on an object.
The fundamental misunderstanding here is thinking that methods are things an object can do.
If you believe that the methods on an object represent the abilities of that object, then of course an Announcement having a broadcast() method sounds silly.
But what if methods weren't the things an object could do? What if they were the things you could do with that object?
If methods were the actions an object afforded us, then it would make perfect sense to be able to broadcast() an Announcement, wouldn't it?