As we all know, Lynn is unjustly insecure about her physical appearance. My personal opinion is that when she makes her standard comment about how Elly has to look like a slouching, paunchy, frowning, dowdy, potato-nosed caricature of a homely old lady who really let herself go in order to make her a sympathetic character, she really means that when she looks in the mirror, she actually sees Elly Patterson's doughy face staring back at her instead of the mildly attractive person she always was.
We also know that Lynn's insecurities march in lockstep with the paranoid dread that all attractive women everywhere are engaged in a conspiracy to steal her men and leave her old, alone and forgotten. This, as I've said, is why she makes irritating and annoying comments about Rod's "harem" and why she had April thought-bubble about how Becky would steal a boyfriend she didn't have because that's what pretty girls do!!
This means that not only are ugly women bad because they wear their defiance of what Lynn views as a norm on their faces, women who outshine the Pattersons are equally evil. This is why we have April foaming at the mouth because of her irrational and counter-productive delusion that a relative innocent like Becky is going to crush her with her star power because that's what attractive people are programmed to do. This is also why everybody anybody should know totally hates Thérèse. This is because it was a given that she was using her beauty to ruin Liz's life because that's what pretty girls do. Given that said "ruin" is what normal human beings would call "forcing a passive lump to move the bloody Hell on with her life", it's sort of hard to support Lynn's premise.
That is, of course, unless you're one of the thousands of members of Kool-Aid Nation who are equally insecure about your looks and equally inclined to blame your woes on predatory beauties. Judging from how KAN and the Yahoovians wanted Thérèse to just die, I'd say that people like Lynn are a dime a dozen.