I’m pretty sure nobody registers their personal smartphone and laptop every time they leave the US for a vacation.
I agree with you on this, but CBP is certainly within their legal rights to interrogate you on the origins of your personal electronics, and they can make a determination that your stuff is subject to duty if it’s over the limit and they don’t believe you are reimporting.
It’s more like the Pope clung on to life just for the opportunity to insult JD Vance. Once that was accomplished, there was no additional reason to stick around.