Try running mvn:dependency-tree on any large enterprise Java project, and see what comes out. If you told me you were familiar with every single library in the output, I would not believe you.
Doesn't mvn show license information?
> If a developer isn't mindful enough to realise that they shouldn't randomly copy-paste library dependencies without knowing anything about them isn't a very good developer.
That's a logical fallacy called: No true Scotsman. In this case - Good developers can be good at some things but bad at other things, so there's absolutely zero correlation between "good/bad developers" and "people who remember/forget to think about licensing".
If you don't consider the GPL to be boogieman, how do you feel about predatory lenders and loan sharks? All of them are just agreements...right?
In a predatory lending/loan sharking scheme, the lender offers their product (money) to people who need it (borrowers) who must agree to extraordinarily high interest rates.
This seems very similar to the GPL since it's just a software agreement that includes extraordinary clauses for developer who "borrows" the product.
Just as easily as it is for a designer to use a copyrighted work. The GPL isn't a boogieman, every project that's under the GPL says so. If a developer isn't mindful enough to realise that they shouldn't randomly copy-paste library dependencies without knowing anything about them isn't a very good developer.