Most things are not absolute truths. Policies can be beneficial under certain conditions and negative under others.
Examples from 100 years ago (ie Great Depression) are not necessarily apt for today's world. Following the World Wars, America was building the world's cars and washing machines, so there wasn't any motive for protectionism. And it wouldn't even have been economically feasible to buy our steel from the other side of the globe.
Fast forward to today, the conditions have completely changed. Shipping has evolved. And steel is cheaper to buy from China because they subsidise the industry and pay their workers crap.
Keynes had a midlife change of heart about protectionism and he wrote a paper called 'economic patriotism'. He basically lost faith that true free trade was possible because other countries never abide by the same rules. They cheat. It doesn't pay to be the only player at the table who isn't cheating.
There's a time and place for increased globalism, and the same can be said for increased protectionism/decoupling.