>>64152363
Very likely. Sure, they might be able to break through it eventually, but never quickly enough to not be met with french reserves meeting them in a counteroffensive.
The Stalin Line was never fully finished and essentially abandoned in favour of the Molotov Line, and even in its planned state would've been a good deal less impressive than the Maginot. And the Molotov Line had barely begun construction and was unmanned for large parts of it when the Wehrmacht overran it.
The Atlantic Wall was far more thinly spread, and subject to overwhelming aerial and naval fire superiority.
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Come to think of it, I can't think of a single instance where fixed fortifications actually succeeded in stopping an attacking mechanized army during a strategic level offensive.
Kursk. Also, as for your example: The Russians having to go around strongpoints of resistance was a huge contributor to them getting overextended and becoming vulnerable to local counterattack.
>>64152417
1. The Ardennes are par tof Belgium.
2. The French didn't have to "tell" anyone, the Ardennes being impassable to a fast, massed motorised push was the general military wisdom basically everyone agreed upon at the time. Even the relatively thin belgian and french present there was expected to be able to delay any attempt for long enough, because the natural bottlenecks of the terrain would've meant that even just basic ambushes, barricades and the odd mine would slow the attacker to a crawl and force them to bring up their artillery to break through.
What they had overlooked was the the krauts were able to substitute that artillery with massed airpower and precision divebombing. Notably, when the krauts tried doing it again four years later in the same place without that advantage, it pretty much went EXACTLY as the French, British and Belgians had predicted it'd go in 1940.
