Versaille played a role, the Nazi's used, and the reparations, for propaganda. WW1 and WW2 were different so, as in WW1 a lot less genozide happened. What was very convinient for both, Allies and Axis, was the coming cold war. It allowed them to quickly forego the necessary clean-up work of Germany, an ugly and lengthy thing, and just go and use former Nazis to continue the "good fight against Communism".

That the Allies choose the Marshall over the Morgenthau plan was a good call so, even if the former would have worked as well including a complete purge of Nazis from Germany.

I'm sure you're able to tell the difference between the guilt of Germany's government and various other collaborators in terms of starting and prosecuting WWI, and how it started, and what it did in WWII.

Observe that nobody was put on trial for the former.

Those monsters took a crushed Germany and turned her into an economical, technological and military power house capable of waging war against the world. Would you "disentangle" yourself from something like that? Remember, they were once popular.

It's a mistake to think you're not crushing a nation's pride and self-respect by exacting vengeance against your monsters. Their restraint was wise and showed they learned valuable lessons.