The two examples that can be used to demonstrate my point are a decade or so apart. The first one has a bored Michael wonder exactly how long Elly's latest self-serving tirade about how put-upon she is and how terrible a child he is will last this time. Rather than recognize that she's perceived as a dreary old nag who can't stand the people around her and who will not shut up about how they disappoint her because they hate her, Elly erupts like a volcano.
The second telling example almost doesn't need a detailed summary: the phone book strip. Why it is that Elly thinks the customer has been rude to her is a baffling little mystery but her reaction of biting through a four-inch thick telephone book out of frustrated rage is not mysterious at all. For some reason, the imagined slight has provoked a witlessly inappropriate respone.
What Lynn loses sight of when she has Elly simply flip out and throw a tantrum like an angry child when she perceives herself as having been slighted is that instead of having made her into a sympathetic everywoman, she's made her into a short-tempered, unlikeable lunatic spoiling for a chance to scream about how awful everyone else but her is.