That’s the barebones minimum, because in those contexts the examples are going to be relatively trivial. Often I find them to be no more helpful than the signature doc itself.
Even trivial examples that actually compile are better than none. because rust uses real code and markdown reading code and docs is the same thing in many cases, no need to even render to html, absolutely minimal markup noise.
I love rust docs. Speaking from many years of using mostly poorly maintained javadocs and well maintained man pages.