We have gone from a deep understanding by nesessity to shallow opportunistic horizontal exploration in less than 3 decades. Until the 90's getting into CS/IT meant knowing your way up from the hardware through assembly and memory layout into higher languages and fundamental data structures finally into an application layer. As computers became more powerful and knowledge started to be packaged into virtual runtime and massive linraries and SDK's. the grounding was lost. and certainly post '00 the exponential rise of the internet changed tech towards stringing together poorly understood googled bits of code that might just work until we pass a test.
Now there are undeniably advantages to both paradigms. But the average developer in industry being in the dark about anything beyond the surface layer, and who's expertise is more about quirks with api X rather than how X would be coded at all is a logical consequence.