If you don't understand how they work, you may end up choosing a wrong container for the job (e.g. a list instead of a dictionary), and you will be tied to find

If you don't understand how they work, you may end up choosing a wrong container for the job (e.g. a list instead of a dictionary), and you will be tied to finding modules that do a specific job in a case when it would be trivial to just write something yourself. In many cases it will be impossible for you to write certain parts of code, or you will end up mashing random libraries together, ending up with a program that works 1000x too slow, instead of just writing a few lines of code that solves the issue. This is especially true for graphs/BFS/DFS and binary trees/search algorithms. Also, without training your understanding of basic algorithms, you may be unable to write a lots of code that goes beyond wrapping over basic libraries. Not to mention being able to write the libraries themselves.