Fair enough, though that's an ask from the State Dept., not a demand from the embassy, as indicated in the OP. It's an important distinction because the embassy holds the authority at that point in the process. They can ignore the guidance altogether or demand everyone open their profiles. They're probably more likely to do the latter now, but they could've done this two years ago too.
Demanding the usernames for the past 5 years and being suspect of anyone not on social media isn't a new, that was my main point. I don't think many people appreciated how shitfucked our visa processes are, even before the current "administration" helping.