Your reply wandered so much that it's rather difficult to tell if you even had a plan for it. I'll take the most
coherent parts of it and try to reply to them:
Yes, you can, especially if you're only vaguely on social networks. But we shouldn't have to jump through hoops like this
If you are so married to your online existence that you consider leaving your laptop behind to be "jumping through hoops" then you probably couldn't be helped by any amount of anything here. Fortunately for you people who are at that level of dependency seldom notice when they are more than 10 miles from their home - as they almost never look away from their screens anyways - so traveling doesn't really matter. As the majority of slashdot readers are far more than 10 miles from an international border, it is reasonable to expect that you wouldn't be a likely candidate to wander far.
when you're visiting friends and whatever while travelling, guess what, social networks are very useful in that case
First of all, if you are visiting other people, that should be your social network, right there. Why do you need to worry about other people at that time? You're taking your attention away from the people who actually cared enough about you to spend time with you in the real world.
Second, if you are visiting people who you interact with in your online social networks, you probably haven't gone some place where you need to worry about a travel mode for your devices; likely you haven't gone more than 10 miles from your home.
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?
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.
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.