All this does it prevent you from assigning a value to it (which, if we're being honest, is something you shouldn't be doing anyway). You can still modify the event's properties through the setter methods, which is an ability you want to have.
As far as I'm concerned this suggestion is just adding a sticky note to the breaker box that says "do not repair." No one was going to be repairing it anyway, but we're absolutely going to go in and fiddle with the switches.