"The person who introduced it was just wrong" is doing an awful lot of heavy lifting in your post. I've seen "this is just the only thing the programmer knows" many times, for instance, in which case one can argue whether an actual "decision" is being made. Certainly "this is the tech the engineer wants to learn" is a real problem in the world, in which case again it's rather debatable whether "necessity" ever crossed their mind as a concern. "I was taught in school this is the one and only way software is designed" is common with fresh grads and they aren't really making a decision because they don't see a decision to be made.

You seem to be implying that all complexity is the result of an informed decision made by someone but this does not match my experience in the field.