You have to understand the mentality of the guys at the top.
They view the sheep with utter contempt.
Their line of thought: "If it is too easy to miss a meeting / assembly / convention, the publishers will definitely miss it. Widespread distribution of a recording of the program will allow them to think they can miss these things with impunity. We must enforce this rule so that these nitwits will actually show up and not relax at home & listen to the program."
I.e., they think that the majority of those who miss their oh so precious and holy conventions do so because they are lazy, materialistic, or selfish - or better yet all 3. They further think that it is only through their eternal vigilence that the rest of the suckers sheep do what they should be doing.
This is what happens when you start to believe your own publicity, that you are the sole 9 people on earth that God talks to.