One the other reasons (aide from the R v. R stuff) for all the comments is we rarely see this situation. Because when, in any similar scenario, a rider is trailing by a small margin in a stage race, that rider will pick spots to attack the leader. BUT, when the attacker realizes his opponent is right in his/her wheel, they know the only outcome will be the leader sitting on that wheel. So they sit up and wait for another opportunity to attack. They don’t keep plowing ahead (unless they want to gain time on other riders) because they know they will end up in today’s scenario. This applies mainly to stage racing.