The social advice older people tend give younger people in the US is often extremely self destructive and isolating.
But to answer your question: How about just not adding everyone you meet at a party at 3 am to your Facebook while drunk? I don't see how this prevents you from meeting people IRL. People managed to get to know each other before social media just fine.
Bonus chatter: When I was almost done with college I had a new flat mate who just started his bachelor's and joined him once or twice when he went out. Usually during college time you don't care about or notice age that much. But suddenly I was surrounded by a bunch of 19 year old freshmen at a BBQ and everyone was constantly checking their phones and messaging people who weren't there. Suddenly an age gap of 6 years that was never an issue before made me feel like a freaking grandpa.
/r/palm
What does any of this say about whether I should be allowed in the US?
FYI software at the border to inspect phone content simply parse the file system and copies over all files for further analysis. It also transfers all emails and more text analysis. Anything flagged by filters get shown to the operator who may be surprised to see so much crap on a visitor device.
(And yes, I'm aware that consular posts do it all the time, issuing fewer visas to people from the wrong countries. States suck, and state violence sucks.)
Edit: I'm not condoning or arguing against the CBP decision, just pointing out that their line of thinking is not novel. It has been around since the times of Socrates.