I think the context was of soon to be college graduates trying to get their first job. Which somewhat makes sense given how little information employers have to go off for those hires to begin with. Once you have your first job I can’t imagine most employers caring too much unless you work in a field like marketing where public perception is part of the job. (And connections to others in the industry are generally a better way to get good jobs anyway if you can swing it)

It seems to be something field dependent. Having a social media presence is an "occupational hazard" for marketing related fields compared to others where it is a don't care.