The trouble I find with all this doxygen-generated "documentation" is that it just gives a very "close-in" view - there never seems to be any "overview" as to how stuff should be structured, etc.
(that may not be the fault of doxygen itself - but is certainly a fault with, I think, every usage I've seen)
and today I saw the above photo, and thought yep, that's how too much software documentation looks: a whole load of tiny pieces all laid out, described, and labelled - but nothing to tell you how to drive the car.
In our work all source is heavily commented with Doxygen for the "nuts and bolts" but for every module we also have separate doc\modname.md in MarkDown that also feeds into the Doxygen process and produces "system diagrams" and more verbose documentation about where the "black box" fits into the overall picture.
it's that second, highlighted bit that's so often missing.