This, as I've said before, is because the only thing that Lynn actually seems to have in common with Elly is that she thinks that her children HATE her and reject all the love in her great big heart because they won't let her prove it. Just as Lynn and Elly take the idea of the kids coming up with their own ideas (which tend to be not going as a punching-bag for Halloween) to be a selfish and cruel rejection of her love, she seems to not want to accept the fact that her children can love her and not let her make them run around with haircuts that make them look as if they lost an argument with a wood chipper. Factor in the fact that she seems to not want to admit that when her children are struggling to get away from her great big love, they aren't being mean but instead fear the end results of her man-handling and we get a huffy idiot who doesn't 'get' that maybe people are right to tell her that maybe she's the problem.
As the Easter strip I linked to reminds us, the problem she really doesn't want to admit that she has is that it isn't really about how much she loves her children at all. Her problem is that she wants to show the world that yes, sir, she really is great at being a mother because she can steamroll her children into complying with her wishes no matter what they might think so praise her with the praise she loves more than life itself. It wasn't about a small child being made to do something horrifying against her will by a vain big shot who wants to show off no matter what the cost might be, it was about a horrible intruder taking away Elly's chance to shine and get the pat on the head and cookie she always wants. It has to be because the alternative means that Mrs Gagnose was right to call her a horrible parent who's too damned brittle and vain to be around children.