Or might they believe me, and think I'm too odd-stream to rent their apartment or work in their office?
They are legitimately my accounts, I just don't use their services. I have a paper list somewhere with over 220 accounts, many defunct of course. Most accounts across the entire internet are, of course, unused or empty, its not going to be unusual.
I was never asked for any of this (well, except github on job applications in the past which never been a problem when I explain them I don't have one) and if in the future I am, I probably will drop the deal (whatever it is) on the spot.
I use email/phone if I want to do something with someone (mostly phone). There may be events like a house warming party that only gets posted to FB, but somehow that tends to reach me through someone, and if they don't, well.. not much is lost to be honest.
To be fair, most of the people I hang out with aren't that into Facebook/other or even if they are, they know I'm not there so they reach out to me/my wife over the phone.
I'm in my early 30's if it it counts for anything.
It's a solved problem, since before the web, and even before the internet.
I'm in a similar situation. The only social media I have is a private Twitter account that I used for about 2 days and posted basically nothing to. People in general seem to understand my choice, though that might just be my social circle. I haven't yet been in a position where I've been asked to provide social media accounts for someone to check my credibility.
Also, other factors are probably relevant. "No twitter" is very different from "No twitter, because I'm married with twins."
We like to conflate large percentages as "practically 100%" but even ".1%" just means "1 in 1000". For large groups even low percentages can represent a significant quantity.