I'll be honest, the evil editor is the one thing I absolutely dislike about this manga. It just reeks of "anyone who criticises my work is a trolling hater", which is a dumb fantasy. Editors aren't like that, he's just doing his job.
Except the other people at his job don’t see him as “just doing his job”—he’s doing his job but also being a complete asshole about it in a way that’s counterproductive to discovering and nurturing new talent.
In other words, he’s a specific character in a particular story arc in a manga rather than a statement by the author about real-life editors. (A mangaka, as it happens, who just got serialized by professional editors.)