Hollywood producer Carol Baum has publicly derided Euphoria’s Sydney Sweeney. Interviewed onstage following a screening of her 1988 film, Dead Ringers, in Pleasantville, New York, Baum described viewing Sweeney’s romcom, Anyone But You, on a plane (“unwatchable”), and said she’d asked students on her producing course at the USC School of Cinematic Arts: “Explain this girl to me. She’s not pretty, she can’t act. Why is she so hot?”

She and her students came to the conclusion they would hire Sweeney if it got their film made. I’m sure the globally celebrated, twice-Emmy-nominated, actor-producer Sweeney will be very relieved about that.

What depressing nonsense, not to mention dire optics. A 26-year-old woman scorned at a screening honouring a veteran female producer, aged 81. A class of students encouraged to join in (such delightful attitudes to teach people going into the industry).

It goes without saying that Sweeney and her work are fair game for criticism, but “not pretty”/ “can’t act”? This is shock-jock-level stuff. Responding via representatives, Sweeney said: “How sad that a woman in the position to share her expertise and experience chooses instead to attack another woman,” which sounds right (to her credit, Baum told the TMZ site that she regrets her comments). But deeper issues are wriggling about in here, that seem to say something (dated, nasty and untrue) about older women, younger women, and how we’re supposed to secretly feel about each other.

For those who don’t know Sweeney, she sprang to prominence in the youth drama Euphoria, playing an uber-sexualised character in a generally sexualised show. Another role, as a jaded rich girl in the first series of The White Lotus, cemented Sweeney’s other interesting work (The Handmaid’s Tale) and resulted in a second Emmy nomination.

Aside from that, there’s the culture war hoo-hah about what Sweeney supposedly represents. For some, her hailing from a conservative-right family background positions her (and her oft-mentioned large breasts) as an anti-PC Republican pin-up, whether she wants to be or not. A recent stint hosting Saturday Night Live (during which Sweeney sportingly spoofed herself and wore spicy outfits) provoked an explosion of entertainingly febrile commentary, including the question: “Are Sydney Sweeney’s breasts double-D harbingers of the death of woke?”

Has Sweeney unwittingly become symbolic of several divides (cultural, political, generational)? To the point she’s morphed into a Rorschach test: as in, what does your opinion of Sydney Sweeney say about you? Do the roles that young actors play (particularly female, but also male) indelibly set the tone for public perceptions? Is this why an equally talented actor, Amanda Seyfried (who broke through as a wholesome girl-next-door character in Mamma Mia!) didn’t endure quite the levels of bizarre “slut-shaming-by-role” borne by Sweeney?

Still, my first reaction to Baum trashing Sweeney remains my strongest: despair. And not just because Baum’s “not pretty” jibe is ironic considering how often Sweeney’s looks are used against her. Perhaps illogically, woman-on-woman misogyny feels twice as jarring as the male variety. As internalised as such misogyny comes across, it can also seem calculated: that, by making a stand against the blonde with the big rack, someone thinks they’re earning feminist brownie points. But the roots of the problem burrow even further into the soil than that.

Put bluntly: it’s disheartening to see an older woman acting like some men presume all older women secretly think all the time. That we’re all just a bunch of embittered harridans who delight in attacking younger women. That we love nothing better than to pluck the wings off the nubile hotties who soak up all the male attention and make us feel bad about ourselves. As the rationale goes: older women are profoundly threatened by younger women and secretly, or overtly, hate them.

It matters because it’s a lie: one of the biggest and weirdest ever told. Kept going by who? Who knows? But there’s no denying it suits a certain breed of male to deploy divide-and-rule tactics. As an out-and-proud embittered harridan, I can assure you it’s all a crock. In my experience, it’s rare for women to be vile (competitive, denigrating) about younger women. On the contrary, they seem much more likely to celebrate them. You only have to look at #MeToo to realise that women, young and old, naturally support each other. Some of us have daughters, and, believe me, being around them and their friends, the very last thing you feel like doing is tearing them down.

This is perhaps what felt so discomfiting about Baum’s outburst. How it seemed to pit an older woman against a younger woman reactivating the toxic myth of relentless intergenerational female hostilities.

I don’t presume to know the workings of every female mind. Nor am I inferring that womankind is permanently engaged in some soppy, hippy festival of mutual hair-braiding and kumbaya (just look at the “Karen” thing). I’m saying older women don’t automatically hate younger women. I’m questioning why the story of older and younger women always has to end up a version of the wicked queen screaming at the mirror about no longer being the most beautiful of all.

• Barbara Ellen is an Observer columnist

• Do you have an opinion on the issues raised in this article? If you would like to submit a letter of up to 250 words to be considered for publication, email it to us at observer.letters@observer.co.uk