Do you think it stops at social networks? Should you leave your phone completely?
Do you really think the two are equivalent in levels of importance?
You don't? Why are they different? Quite a few people communicate almost exclusively by text, by chat mediums with the people that they know. Some people don't like phonecalls. For an increasing number of people they are absolutely the same importance.
Social networks today, your phone call history tomorrow? Is that OK?
There are nations that for years have checked visitors' phones at customs. In case you didn't know this before, US laws don't travel with you when you enter another country - you enter another country and you are now expected to adhere to their laws. If you don't like their laws you should have traveled elsewhere.
That doesn't make the procedure good or right. Jobs and family often force travel. Anyone who has a distributed life doesn't get to smugly avoid it.
You can do this at the moment. Then tomorrow when they start doing automatic searches based on your name, and show you an account they've found that looks like you and has your name, what then?
What are you talking about? This is quite a bit removed from the topic at hand. If you're worried that a foreign nation is going to ask you to log in to a social media account, then you've made yourself a slave to social media. I'm guessing you don't leave home often with that attitude, though so you're probably just fine with that.
"If one would give me six lines written by the hand of the most honest man, I would find something in them to have him hanged."
FYI (to correct your many assumptions) I'm British and have to travel to the US and other countries to see family. So yeah I'm very aware that I have no rights at the US border. If *you* don't care about rights at borders then I would say it's far more likely *you* are the one that doesn't travel.