> That would hold true for whatever systems.

Remember how you started with how every UI system and framework was somehow this separtaion of style and presentation and structure and interactivity?

And now it's "they are never separated, and this holds true for whatever systems"

> The pretention is just for making it easier to do the job without extraneous effort.

In reality there's a lot of extraneous effort especially when systems become more complex. BEM was invented not because CSS was great and amazing at reducing effort, but because it was adding a great amount of effort for a very large number of designs.

CSS Scoping was finally, thankfully, added not because cascading nature of CSS reduces a lot of effort.

The rest of your comment has nothing to do with what I said.

> And now it's "they are never separated, and this holds true for whatever systems"

What I described as separation is a a decomposition into modules which are linked together through a contract. CSS has cascading and selectors, while JS has the DOM API. Otherwise, it would still be attributes on tags.

BEM is just a development technique, not a technical requirement or capability. Without cascading, we would probably have components and inheritance.

> Remember how you started with how every UI system and framework was somehow this separtaion of style and presentation and structure and interactivity?

On Android and iOS, you have XML for layout. QT and GTK have support for CSS like styles. I remember at least one of the have supported XML for layout definition. They're not required, but they make it easier to build the UI as it almost always have a tree structure.