The authorities can easily decide your "harmless" social media account is something doctored up to fool them
Correct. Admission of non-citizens into the US is a judgment call. A doctored-looking social media account may be even worse than no social media account at all. I'm not sure why you consider that a problem.
The traditional way of dealing with visas is to require solid, credible foreign government records (including police reports) and simply refuse admission to anybody who can't provide those. That means no admission from politically unstable countries at all and no admissions from countries whose governments we don't trust. Would you prefer that? Or would you prefer that US immigration officials give people more options for establishing that they might be admissible after all?
Perhaps I was not clear enough. My point is that if you are someone that rarely uses social-media or a professional that keeps it very sanitized authorities might just make the judgment call that it is a doctored account. I was just point out to the OP that a social-media presence is not necessarily in your favor