We don't have a widely-understood cross-cultural shorthand for annotating an item's 'newness'. By contrast, we are all familiar with objects retaining their identity while they move.
When I minimize my window in macOS, it physically transforms and is sent to its new location. I know where the window I was working on went, and I as a person would have a good reason to be able to somewhat or even mostly comprehend this even if I hadn't ever seen macOS before.
With no animation, the large and prominent window I have been using would immediately disappear with no indication where it went, and the minimized icon in the dock would be highly likely to be overlooked. It would also look almost exactly like "closing" the window, and it would be easy for an inexperienced user to think minimizing a window and closing it are the same thing. I can assure you, this blurred conceptual distinction is not an imaginary problem.
Sure, I don't personally need this animation because I'm an experienced user already. However, in almost all cases it is fundamentally flawed to approach interface design by considering only the needs and preferences of experienced users.