There likely is no point, at least not one that those of us forced into this game will care much about. [Since...they were all just dragged into this mess...] Though I would hazard a guess that the reason why they could not attack us directly until now is a matter of the rules Sans alluded to in his summary. He did say Wrath was the only one not following them, and her altercation with Undyne is the only thing I can think of that would qualify.

[He frowns more deeply and lapses into silence once more. You guys keep talking, he's gotta sit here and think and try and fit these pieces together.]