It's a silly rule because it's about the wrong thing. You can draw away without starting a transition - it just makes it harder for whoever was trying to follow you. Much better to have a rule that's actually about where the transition of who is in front occurs.
The inefficiency of riding in a staggered line is punishment enough - making a rule against it just pointlessly punishes people who do it by accident.
It's a silly rule because it's about the wrong thing. You can draw away without starting a transition - it just makes it harder for whoever was trying to follow you. Much better to have a rule that's actually about where the transition of who is in front occurs.
The inefficiency of riding in a staggered line is punishment enough - making a rule against it just pointlessly punishes people who do it by accident.