Because they wanted everyone to describe hand chasing scenarios in which they could spring a "gotcha" moment and claim that counter punching is the correct answer after all. Problem is it isn't, the counter punch will likely fail as well because you are already a step behind.
No "gotcha" about it. This started out with me kindly replying to Geezer about how the center guard fails. The diagram was made to illustrate the point about this guard.
You can do something other than the center guard. But if you use it, the only options are chasing arms and/or getting hit.