Comment by hobofan

I think for the next 20-30 years it still wouldn't be feasible to make it a red flag due to a non-negligable part of the older population not being on social media at all. I assume it is right now still be possible to enter countries with a mobile phone number, and those have existed for longer and are used more widely than social media accounts.

I would assume they also try to derive associations to social media accounts via passport information if you don't provide any to them. So I think it's rather an additional bureaucratic step added on their side rather than a red flag.