Yup.
In the web world we take content and form and create something as a whole - the end result is a ‘product’ in itself, but it’s still the SUM of content, interface and function. There’s no escaping that, but then it isn’t a problem anyway.
If anything the distinction is becoming more clear with positive trends in removing the device from the equation. You gave a great example with ebooks, but this factors into everything on the web - BB is a good example (ironically) - the ‘form’ is different on a desktop and a mobile, but the content remains the same, the content shouldn’t change to meet the design, the two are separate parts of the same whole; one is there to facilitate the other.
Creating a unified ‘experience’ works on something like a marketing site for beer, but not so much for anything ‘content-driven’ (these words have uses). I also don’t see how this compares to media like film, if I’m honest, it’s apples and pears. Websites are generally created specifically to HOUSE content, films aren’t created to house a story, they ARE the story. A better comparison would be websites to cinemas, and the film itself acting as the content.
Some people just think too much about problems that don’t exist.