I read that Ron Unz essay. What a fascinating mix of genuine fact, half-truths, distortions, and strawmen.

If I had to rank it on a scale of 0 to 10 where 0 is a complete tissue of lies and fabrications ("Donald Trump is a Russian spy! Saddam Hussein attacked the Twin Towers!") and 10 is as close to pure truth as is humanly possible (the truth, the whole truth, and nothing but the truth), I'd put it about 7 or 8: mostly true but with a fair amount of spin that makes it a bit misleading.

Needless to say, no, not everything I know about WW2 is wrong.

Sure, if you're one of the hoi polloi who think that Hitler was uniquely evil and solely responsible for everything bad that happened in WW2, and wanted to "conquer the world", and the allies pure innocent, then you might learn a few unpleasant truths. But anyone with serious knowledge of WW2 will already know that (e.g.) Hitler admired the British and hoped that they would ally with Germany.