> by directly letting people modify the source code (Unreal Engine, Godot).

Unreal is not open source, and while Godot is, I would wager 90% of its users never even look at the source code. It very specifically attracts people who want an easy way to make games without prior expertise.

> Players do not care about that.

Users don't care about much when it comes to software quality, honestly. They accept 20 FPS, slow loading, bug-riddled games that consume +20gb ram and +100gb more disk space than necessary. They may complain about a game if it gets bad enough, but they still buy and play those games. My games are significantly more optimized than most. They aren't perfect, but they don't need to be. They don't even need to be as optimized as I have made them, it's mostly just a point of pride and making the kind of software I want to see in the world. I think the only way you lose a player on technical points is if they literally cannot boot your game, but those issues plague engine games too. I had driver issues myself crashing on boot with an UE5 game two weeks ago.