One important thing to consider (and I'm not sure that the survey does) is that a lot of this weight may come from cached sources, such as javascript libraries

One important thing to consider (and I'm not sure that the survey does) is that a lot of this weight may come from cached sources, such as javascript libraries sourced from CDNs. While more libraries = more total content weight, using common libraries may reduce the weight of the content that actually gets loaded, by eliminating the requirement for redundant compatibility boilerplate and providing DOM manipulation tools that allow much of the page content to be created client-side.