It's true that there should be no need to write these things yourself. The alternative C++ gives is not really tempting. A language designed for demanding game development doesn't exist (yet), so one evaluates which is the least worse option.
I think this is one of the biggest disadvantage of a mostly standards based, no particular organization in charge type of language like C, as opposed to, say, python.
I am fortunate that, at the moment, my needs are mostly casual and very rarely performance focused. If I needed C I would just STFU and use C, accumulating my own workarounds for the dispersed nature of its resources.
Qt, I believe, also comes with a bunch of "standard library" stuff unrelated to UIs.
In my experience, most of the people who say they don't need OOP or generics end up implementing a limited (or even a full-fledged) version of these things themselves.
Much also depend on how much you really need dynamic allocation - it can be optional.