Montgomery's insubordination would be punished if it happened today. It wouldn't be met with Ike's mild "Monty, you cannot talk to me that way. I am your boss"...Montgomery mostly was a glory hound that was obsessed with not being a footnote in history behind the other great Allied generals like Ike, Patton, and Zhukov. Other than beating an ill supplied Rommel, the only thing he accomplished was the blunder known as "Market Garden". Eisenhower only gave into the dumb idea to show Monty that he still mattered... Yes Monty still thought in the early WWI strategies of "It takes just one good punch".
That's a double edged sword. Most of his generals in the early going were very conservative, and were more concerned with the numbers and lack of experience of the Post Versailles German military. I mean at the time of the invasion of the Sudatenland the German armor was still 80% horse driven, and many generals were hesitant of a possible war with major powers. More or less, Hitler's meddling actually probably defeated France. His problem(s) was that he probably put the absolute worst person in charge of the Air Force and Versailles destroyed the German navy.
Where Hitler's meddling ultimately costed him was on the Eastern Front, and how to handle the USA-Japanese conflict. But he did relinquish command to the Army in 1943 after the disaster at Stalingrad. But Mannstein vs Zhukov was a mismatch in men and generalship. After Kursk, everyone was trying to find a way to just "not lose" the war.
A war with Russia was probably inevitable because there are sources that lean towards Stalin planning a betrayal against Hitler in the next few years. So maybe Hitler was right in that he stood a better chance in going for a surprise attack, but he should've destroyed Monty in Africa before attacking Russia. But still he probably signed his death warrant with him standing by the Japanese after Pearl Harbor.