As I had mentioned in a previous thread that has come up recently with regards to UE5 and being open sourced, one of the greater sins of Unity is that it is mostly closed source.

In reading through the blogs of some of their developers, they seem to have a contrived idea that people "shouldn't have to know how it works", which, while it's a noble gesture, is bullshit because by prohibiting reading the implementation you can't know how it works anyway, whether or not you want to.

The domain model in Unity is fundamentally broken because it forces you to tie a lot of logic to a Component. People end up embedding all kinds of unrelated bits and pieces of functionality to the Camera because, well, where else are you going to specify it? This is a batshit crazy way to write software. Yet here we are.

Lastly, engines are leaky abstractions. Most software is a giant leaky abstraction as bugs and other things tend to creep up from beneath you, and knowing how something works down to the minute details is a huge advantage when it comes to not only debugging, but developing (architecture, style, optimization, whatever).