If you've heard it from different women, perhaps it's because it's a real issue. The assumption (by men) is that she posted a photo of her self in order to be attractive to men, and to garner their approval. In fact, according to her own words she posted a picture of herself enjoying her day, which just so happened to have taken place in a bathing suit. She isn't inviting their commentary on her body just because she posted a picture of herself showing some skin. The assumption that a woman only exists to be pleasing to men is the issue. That's where the objectification comes in. A woman's body, sexuality, personhood, etc., exist for herself. Just because that happens to be taking place in public, and wearing a bathing suit does not change this.
"When my husband and I used to go to what is commonly known as a “swinger’s club” there was frequently a lot of sexy clothing and sexy behavior going on, but the atmosphere was also very empowering to women. What they wore or how they danced did not necessarily convey to others sexual availability or enticement. It was not for the consumption of the other people at the club — it was for the individual. People looked at each other and admired each other, but as human beings expressing their sexual sides, not as objects."
