Abstraction is about coming up with general designs from many specific implementations. You can layer abstractions but layering is not fundamental to abstractio

Abstraction is about coming up with general designs from many specific implementations. You can layer abstractions but layering is not fundamental to abstractions. Just because a design introduces extra indirection into a system does not mean that the design is providing any abstraction. Likewise just because a design changes from one implementation to another does not mean anything has been abstracted. Your example of moving from DOS to Windows is really good for illustrating this. DOS had almost no hardware abstraction support, you had to include drivers for a lot of hardware into your application. Moving from DOS to Windows 3.1 only provided abstractions over the video drivers, for example when it came to network cards you still had to use DOS drivers. Moving a text editor from DOS to Windows does not provide you with any abstractions for things like the cursor. It is only changing the API for the sake of having your text editor run on a different platform. Guess what? This is the same with trying to get your cursor and text rendering working on a web browser. There is absolutely no abstraction here, you are just changing your code to work with the very awkward DOM API.