it’s less that English simplified them and more that it never developed case marks for them.
Well, Old English baggs to differ. English lost its case markings on articles early on and kept them on nouns a while longer while German kept them on articles and simplified nouns much more early on.
In contrast, not only German repurposed the demonstrative “der” (that, which, who) into an article in a cleaner way
… as did English with “se”/“þē” which started as a demonstrative the same way der/die/das did.
but it’s also dumping most grammatical case info into the article
Again, German didn’t dump anything into articles but rather lost it everywhere else.
There is this idea that this fostered the process of using der/die/das much more often (which made it from a demonstrative to an article) but I disagree because it was a widespread process, not only in German but in huge parts of Europe, including beside Romance languages also English were this reasoning doesn’t work (as shown above).
You got it all wrong! Babbel is an app to learn other languages, no punishment of any sort.
Just kidding, it’s an app to make monkey, not to help people.