A div element is a node in a tree which will be rendered by your browser in the way specified by the spec. You absolutely can’t freely do most of the actions you list to a div. There are severe limitations.
A div doesn’t at all emulate a class. Its semantically something completely different.
> A Rectangle component is a node in a component tree which will be rendered by your OS graphics library in the way specified by the spec. You absolutely can’t freely do most of the actions you list to a div. There are severe limitations.
It seems like you're just talking about a `Rectangle` in the abstract rather than the real limitation that even `class Rectangle` is subject to the rules of the runtime engine that renders said `Rectangle`...in a component tree...with the restrictions of the OS/GUI framework...
No.
Rendering outside of a web browser gives you a lot more freedom when it comes to how you layout and render. Rendering engines don’t necessarily use components tree by the way.
Even gui frameworks (which is what I think you are talking about with OS graphic library) have layout engines which are a lot more powerful than css. Flexbox is a step in the right direction but still inferior to what some frameworks could do 20 years ago.