It's worth saying that "sexy" is not translated well in other languages and cultures. It was very common in Thailand and Malaysia while I lived there to hear parents and relatives say their child was 'sexy'. I wouldn't be surprised if it also made its way into Chinese-English parlance as "visually appealing" rather than "I'd fuck that".
Article says "young people", but curiously only cute women in the pictures.
I think it is just cute woman get more likes on social media. Since it is not formally a movement, more like humorous complains, cute woman tends to get more attention in this case.
sexiness
Chinese "sexy" is not as formal as their american counterpart, I think she said "可爱而不失性感", which I feel is a perfectly SFW phrase. And like others have already said, it is probably also a subtle dry humor that got lost in writing and translation.