> Most people have an online profile, so what's preventing the interviewer/hiring personnel from just looking them up online?

Citations needed. What % of currently alive humans have an 'online' profile, how are you measuring that statistic? Are they engaging actively? How many have never had a smartphone, how many do not use social media at all?

Without sources and actual numbers it's hard to take your point seriously. MOST people do this on Hackernews, claiming "most" or "everyone" or "the majority of..." without actual data to back that up.

I've never bothered to look up pictures of candidates online. I read through the resumes on greenhouse can click proceed or reject. Eventually I see them, but not until the actual interview.

But you were probably not hiring for roles were being attractive, friendly, used to being in front of a camera and (possibly) extroverted were important, right?