YepThe problem is the scenarios are all binary and total, WW2 style, rather than having any sort of subtlety that was possible until as late as 1917 in many circumstances. There is little consideration given to options other than the simplest and most absolute, like beating France in 6 weeks and the war over by Christmas.
The fact of the matter is that unlike WW2 WW1 can be won by the CP by military means, the correlation of forces and balance of power does not put it beyond their grasp and a reshuffling of the deck chairs can produce results. I think people know this, which is why East First threads come up so often, the problem is that while CP victory is possible east first isn't the way to do it.
And if nothing else proto-Germany has already managed to get in quick and beat France in living memory, in a result not many at the time were expecting. So in abstract it's not some unknowingly impossible thing to do (yes obviously 1914 is not 1870 for all sorts of reasons but that works in both directions). However one of the bigger differences is in 1870 the nascent Germany had played a much better political game prior to the conflict starting.
Honestly I kind of see parallels to the question that gets asked of Barbarossa in 1941, yes we know now it was a bad idea, and we know that given the reality and errors in German planning and assumptions it was a bad idea. But in 1941 in Germany it looks like doing the easy thing they had managed to do in the last war* having just succeeded in doing the thing they failed at in the last war.
And in fact in abstract when it comes to a quick advance into France followed by quick victory Germany is 2 for 3 in a 70 year period. So this isn't some impossible dream, even if it does rely on everything going right and the the French not doing well. That said I think you could argue that by the last week of July 1914 enough things have already not gone right for the Germans even before the troops start crossing borders.
*don't want to draw too closer a parallel here it did take them 3 years in 1917