Yes I am in fact saying precisely this. The German army does not have the logistical power in 1914 to advance the distance required by the plan and capture Paris, period. It's not there, and it certainly won't be there when Germany faces two invasions at once. Germany made several bids to directly knock France out of the war, the most famous being the Battle of Verdun. What happened there was that the Germans discovered the French were far stronger than what they expected them to be, and this pattern holds even truer for 1914, when the war is mobile, and before the massive losses of 1915-6.
Here is the problem, things happen from time to time that cut and dry rules say shouldn't happen. Removing the BEF and as late as 1912 (I believe, could be wrong) the BEF isn't going to be much of a factor till D+30, if not longer. The Germans discounted the BEF and other times counted them in. It all depends on the inputs and assumptions you make.
No BEF changes movement rates and locations of German troops. Remove BEF and there is no Battle of Charleroi or Mons anything like what happened. Maybe French 5th army gets away as historic, maybe it gets more damaged, maybe it gets pocketed and destroyed. Worse it changes the Battle of the Marne, Germans are still going to be over stretched but lack of BEF is going to make the French weaker.
The objective of the S plan wasn't to take Paris. Of course the Germans might try if they get that far. The objective was to destroy the French army in the field. Plan XVII was what the Germans wanted the French to do.
The one thing you are forgetting about the two invasions the Germans stopped them both cold and blooded the French and out right trashed the Russian.
Would you care to clarify what you are talking about with respect to the Germans finding the French better in 1914. I really am not sure where you are going with this.
The problem is 1914 they cannot pull it off. Their armies were being logistically overstretched well before they even neared Paris. The Germans did not have the manpower to meet the French invasion, Russia's invasion, and to both mask Antwerp and push through Belgium and France alike to fight French troops.
Since the Germans were doing all you subscribe till the tide turned at the Marne, you under stand if my view point is you are overstating the manpower issues. The French had their own problems and lost heavily during the battle of the Frontiers.
In fact there weren't even enough Germans to mask Paris in the first place. The Germans took casualties at Liege, at Mons, at Charleroi, Namur, Morrhange, they had to equip and supply army groups whose leaders were mutually incompatible.....
The French also lost heavily and the was if memory serves no mobile force in Paris after the reservist were sent to the Front (IE Battle of Marne) there is little need to heavily screen the French capital.
The plan as directed is an inherent no-go. They cannot win in 1914 with the existing plan, facing the existing reality. A different reality means a different plan and thus a different war.
The Germans Generals of the time had another viewpoint, they tried it and came close to success.
Michael