And the same is true of the dev who copies tons of code from stack overflow without really understanding it. When issues like thread safety of the app come up, that dev is going to be lost.
Experienced musicians choose loops and samples understanding full well the trade-offs of quantization and timbre. Experienced devs bring in libraries understanding the trade-offs. Answering the question "how well do I need to know this library before introducing it in production?" is a really, really hard problem.
In practice, I see junior devs blindly copying code that subtly won't work more than I see them writing their own DI system because of not-invented-here syndrome. But, admittedly, the latter tends to be more destructive.