I only did a quick read of permit.io offering but iirc they don't focus on hierarchical data. If having access to a resource cannot grant access to unbounded number of other independent resources (eg sharing a folder) then almost all issues of the article disappear
Scales both on the tech, and on the human side - e.g. your product manager can add roles (with CI approval) without requiring engineering involvement.
(I'm biased but still true)