You know that Game Engines commonly are used by programmers, because it is also some kind of a “library” or framework to develop games? Sure you can do some things without coding, like designing levels (I count Blueprints to coding, because it is same logic). Game Engines aren’t a simple thing, you also cannot compare them to like photoshop because this is a pure user program. And if you use Unreal Engine to edit images you are doing something wrong.
PS: There are many people who understand how engine works.