> This is dystopia in the making, 1984 coming alive, first of all; why someone's social media activity would be the matter of the government?
I don't know that it's specifically required for a visitor visa, but 'Good Moral Character' is required for naturalization in the US. Activity on social media is probably an indication of moral character, so it's not unreasonable to check social media before issuing visas that have a path towards citizenship. Student visas may technically be visitor visas, but there's a clear path F-1 -> OPT -> H-1B -> EB-2 or EB-3; if you're going to check on moral character at the end of all that, you may as well check at the beginning too.
What constitutes good moral character might not be a great question for a government to decide. There is certainly potential and precident of the government using good moral character as a proxy for discrimination that has nothing to do with morality.
I don't know that it's specifically required for a visitor visa, but 'Good Moral Character' is required for naturalization in the US. Activity on social media is probably an indication of moral character, so it's not unreasonable to check social media before issuing visas that have a path towards citizenship. Student visas may technically be visitor visas, but there's a clear path F-1 -> OPT -> H-1B -> EB-2 or EB-3; if you're going to check on moral character at the end of all that, you may as well check at the beginning too.
What constitutes good moral character might not be a great question for a government to decide. There is certainly potential and precident of the government using good moral character as a proxy for discrimination that has nothing to do with morality.