Among other claims related to the concept of sexual objectification is the assertion that display of women in sexually suggestive clothing and portrayals by media outlets like fashion magazines contributes to people's tendency to sexually objectify women in everyday life. They complain that this specific type of sexual objectification hurts all women by normalizing a focus on women as sex objects.
Complaints related to objectification have become pretty mainstream in the female population, even when women aren't actually being objectified. For instance, some women fail to differentiate between noticing a woman's appearance, and treating her as a sex object.
There is also the complaint that these magazines communicate unhealthy standards for beauty, requiring models to maintain a physique that is unrealistic and dangerous for women to attempt to maintain. Many women have made their voices heard on this - they want to see popular media using models of different physiques, representing more of the female population.
Elle Magazine's November cover model should have satisfied both of these interests; she's not a thin woman, and though she looks quite lovely in the image, that appeal is not achieved by placing her in revealing clothing and a sexually suggestive pose.
Instead, some women saw the cover as another opportunity to complain: OMG! Elle Magazine didn't sexually objectify Melissa McCarthy because she's fat! How dare they!
Seriously. That is the complaint, boiled down from an article-length rant to its basic nature. McCarthy was wearing a coat. It's not tight-fitting. She wasn't showing any skin. She wasn't showing any tits and ass. The pose she's in isn't suggestive... therefore the cover is bad.
So in addition to the rules "Don't show women in revealing clothing and sexually suggestive poses" and "Use models who aren't skinny" there is now also "If you follow both rules at the same time, we're going to complain about that, too."
And we wonder why we have a reputation for being unable to make up our minds?