think the downvotes are because of relevance. point was not using advanced rust features, not being documented

I don't see how the relevance is in question. GGGP said "There's actually a decent amount of comments (for rust code)." GGP seems to be responding to that parenthetical.

Javadoc pioneered this 25+ years ago and despite that, there's plenty of poorly-documented Java code out there. Orders of magnitude more of it than all of the Rust code in existence, in fact.

Intuition tells me that Rust is young enough to attract a certain type of early adopter, the kind of programmer who is more likely to document their code well from the outset.