History

Yeah it is unfounded to say '42 would have been possible and didn't occur do to sabotage by the western allies. The Brits did seriously hold off on opening a second front to be sure, but that went for Operation Torch as well. The US had hesitations and wanted its imperial vengeance war in the Pacific, but people like Eisenhower pushed hard for supporting the USSR. Thing is D-Day was not something you could just do, even with months of build up. They had to do Operation Torch and clear out Vichy forces and Germans in North Africa in a manner that was utterly untested and experimental.

Then they needed to do Operation Husky and invade Sicily which was another immense task and involved the shifting of war production all towards LSTs for invasions, as well as being a real joint operation between the US and UK which got very messy. Nothing to do with the Soviets with why Husky was harsh to plan, it was plain old British stubbornness and an open attitude of honor and ego mattering more than anything. It also involved a shift in planning between the army and navy which led to some fights between commanders and the captains of ships who would be responsible for their landings.

They D-Day gets postponed due to weather and Churchill's incompetent dick-measuring at Anzio and waste of LSTs at a time when Eisenhower was literally trading units with the Pacific in exchange for a handful of them. The logistics of all of this, the complicated relations and red tape, it cannot be understated.

One of the best histories I have ever read and probably the most readable history book is Craig L Symonds' "world war 2 at sea: a global history" I HIGHLY recommend people buy it asap. Doesn't matter if you like naval stuff or anything, do yourself a favor and check it out