I submitted a DS-160 application for a B1/B2 this past Friday and which asks for all social media handles in use over the past 5 years. The implication is that this a request for accounts you've used, not those that are still "active".
Yes, such a requirement for my visits to the US would also motivate me to not open any new social media accounts if I was planning on visiting the US within the next five years.
