The Maginot Line was actually a complete success and worked exactly the way it was supposed to. The taunt would be a "Dyle Plan" or "Maurice Gamelin" coin. Gamelin came up with the Dyle Plan for the northern half of the battle which left the French army exposed at Sedan and resulted in the fall of France.
Well, it worked until the Germans went AROUND it and behind it.
Well, that was the entire point of the Maginot Line. "Hey, we've got this big ol' wall of death here; go attack us through Belgium instead." In that role, it worked like a charm. The problem is that Belgium's ginormous fortifications fell like ten-pins instead of holding out. Since they were the same design as the Czechoslovak forts that fell into German hands in 1938, the Germans knew them inside and out and had determined how to beat them, most famously Eben-Emael which, with a garrison of over 1000, was supposed to hold indefinitely or at least destroy several critical bridges before the Germans could ever reach them, and instead fell to less than a hundred paratroopers - or rather, glidertroopers - in a single night. The complete rout all along the front panicked Gamelin and likely helped motivate him to push the entire French strategic reserve into the Dyle plan, perhaps believing that the Germans were following the original warplan by Halder which the Belgians had captured in January. This left absolutely nothing to counter the main German thrust when it came roaring through the Ardennes.
Though, honestly, if Gamelin hadn't overcommitted to Belgium, we'd be discussing how stupid the Nazis were and the reckless incompetence of Manstein and Guderian, not to mention Hitler for overruling the entire OKW to authorize their plan instead. The German army was in complete disarray in the Ardennes for an extended period, and their logistics were terrible - when people say the Ardennes aren't tank country, they're actually right. A well-timed counterattack there would have destroyed the core of their armored forces, while they had already been stopped cold in Belgium at Gembloux. It was a horribly reckless gamble, and it only worked because their opponents moved exactly as they hoped and lacked the responsiveness to counter in time.