That's right, both before US Consulates when applying for visas, before CBP when applying for admission, and before USCIS when applying for a benefit (H-1B, O-1, green card, etc.), social media is being reviewed, not across-the-board but more and more. And there's really no option to keep social media as private if asked to turn to public by a Consular Officer or CBP Officer. The review is broad and not limited to social media that is critical of US policy but extends to a review of an individual's entire background to make sure there were no violations of US immigration law, including unauthorized employment.