I suspect that you're implying that the user doesn't really care about the underlying technology of the site. You're correct, but whether they realize it or not, they are still reaping the benefits.

As an example, responsive design allows small businesses that may not be able to afford to build multiple versions of a website to instead create a single site that provides multiple experiences based on the type of device used to view it. Users win, whether they care about it or not, because they can now use the site on the device of their choosing, without worrying about it being functionally broken.