The article you linked makes a slam dunk case that Smoot Hawley and Protectionism did not cause the Great Depression (It only raised tariffs from 44% to 53% on just one third of US imports - and those imports effected by Smoot Hawley only totaled 1.3% of the US economy).
Smoot Hawley added less than one tenth of of percent additional cost to the economy, and did not even noticeably effect the volume of imports that it covered.
The article points out that the Federal Reserve reduced the money supply by one third, between the 1929 stock market crash and 1933. That is a huge (the real) cause of the depth and length of the Depression. But that was the Democrat’s policy mistake, so they need a cover story to deflect blame.
The article did not mention the initial cause of the October 1929 Crash (which is also why the Depression was widespread around the world) - the collapse of the British Pound, which then was the Global reserve currency (after the Leftists swept the May 1929 elections, and Labour Party Prime Minister MacDonald took power).