Then allow me to enlighten you.
You see when countries have large amounts of people uneducated in macro economics who can be easily manipulated, a populist politician (who probably knows better or at least has access to people that do) can make simple claims that appeal to their sense of nationality and "trade fairness" in order to do thing's that ultimately are probably more damaging to that countries future (and those same voters job prospects), but still help that politicians popularity in the short term.
Compound that with the fact that said politician has already proven several times over that he doesn't care about the damage he is doing to his countries economy, relationship with it's allies, or even standing in the world, and you have a recipe for many other short term populist moves that help him win votes.
Heck we're actively working right now to build a wall between us and about the ONLY source of labor willing to do large amount of undesirable jobs no American wants to do! Including but not limited to: cleaning toilets, mowing grass and picking fruit in the hot sun.
Don't expect this to be the last tariff you see coming from our leadership.
And yes technically you are right. China's government was subsidizing the cost of (mostly) low value goods they produced so that we Americans could take advantage and pay the Chinese even less than we should have and keep more of our money. And now we have thrown that away, so that a few American fat cat corporations can take more money out of the pockets of Americans instead.
But you see, that explanation makes a voter's head spin. It's just so much easier to say "China's stealing our jobs! Lets do something about it!".