Power does tempt people to abuse it, and they regularly give in to that temptation. While I’m not in agreement with the person you are arguing with, I do believe people cannot be trusted with power, and therefore there need to be checks, and recourse, and the more power a person has, the more they need to be monitored rather than trusted. (Police are an example. Politicians are and example. Hollywood producers area an example.)
There is also a selection mechanism at play. People who like to abuse power seek it out.
Hierarchical taxonomies always run into problems because there are multiple equally valid ways to organize things. Hierarchies are inherently a wrong-headed approach. Subjects are inherently multidimensional. Hierarchies wind up forcing you to stack categorization on different properties on different levels of the hierarchy and it winds up arbitrary which ones you preference over others.
The tendency to reach for hierarchies is a bias we inherit from life in the physical world. A physical object can only be in one place at a time, so we organise physical objects in hierarchies by necessity. Rooms, cabinets, drawers, files. This is not a necessary limitation on computer system but people keep insisting of using them anyway.