The purpose of the project is to show how a high quality game can be created. It is educational project, finishing the game is not the main goal. The series are on ~600 episode. Which is around 800 hours. I don't think that is much considering that
- until episode ~200 soft renderer was used to show how exactly rendering works, then he switched to openGL.
- he is diving into complicated topics, like right now advanced light system.
- ~50% or more of time is spent on detailed explanations.
A high quality game can be created in Unity, Unreal or Godot. No one needs to know how to implement a renderer from scratch to do that.
I'm not disputing that Handmade Hero is valuable - there is a lot of good theory and insight into process there, but what it does not teach is how to make a game.