It may not be perfect for all cases (e.g. if some sort of dependency is linked but not present in the source tree it is naturally not really accounted for by Debian copyright files) but then there is always the options of either adding copyright information to every source code file (I don't like that style for redundancy but it is for sure a very clear way to do it) or to hand-craft a human-readable variant similar to the Debian approach but less formally.
In any case it seems that nothing is new aobut this and developers working with FOSS software should very well be aware of these concepts.
It may not be perfect for all cases (e.g. if some sort of dependency is linked but not present in the source tree it is naturally not really accounted for by Debian copyright files) but then there is always the options of either adding copyright information to every source code file (I don't like that style for redundancy but it is for sure a very clear way to do it) or to hand-craft a human-readable variant similar to the Debian approach but less formally.
In any case it seems that nothing is new aobut this and developers working with FOSS software should very well be aware of these concepts.