You're repeating advice for people with zero experience in making games, which is fine. But it doesn't have much to do with this discussion. Casey Muratori is

You're repeating advice for people with zero experience in making games, which is fine. But it doesn't have much to do with this discussion. Casey Muratori is not teaching people how to make an indie game or an AAA. He's teaching how to make almost everything in a video game from scratch. He speaks constantly of how he's not a game-code programmer, let alone a game designer. Pretty much everyone watching it knows what they're in for, because he talks about it all the time. Those ready-made engines you're talking about have to be made by someone. Not to mention that anything beyond "basic indie game" requires someone who knows deeply how a game works. And those people are who Casey is currently educating. Someone doing Unity/Unreal for several years won't learn those things Casey is teaching unless they really dive into deeper material, and Casey is providing exactly this kind of material. This industry doesn't need more people with Junior-level experience even though they've been working at it for 20 years. Maybe this kind of education not you, and that's fine, but just because something is being taught on the internet, doesn't automatically mean you and everyone have to learn it. You gotta learn to live with it.