When government interferes with the free market by using tariffs, you end up with artificially higher prices which harms the average consumer. Capitalism is about managing your resources effectively to deliver a quality product at a competitive price. Tariffs and isolationist economic policies erode the efficiency of the market to the detriment of the individual consumer. That is not capitalism. That is government beauracracy pushing us towards another depression.
Note that a variety of laws and regulations discourage monopolies and so-called anti-competitive practices. These result in greater competition, and, presumably, lower prices. So capitalism is restrained by regulation. As a consumer, you benefit - but as an owner, you lose.
And if tariffs and isolationist policies are bad for the market, they why is China - which does restrict access to its markets - growing so fast? Hmm?
Free trade is a dagger in the back of America!