I keep wondering about this too, perhaps the intent is that there's some known component that works well with the ux goals - so if someone builds a native application (with vala), they can reference the eos 'web' app when implementing a web view.
It's still something I'm leary about. I switched from a mac to ubuntu (gnome) recently, and wonder how much lack of facilitation/communication leads to so many separate or incomplete apps. For example, I may use the gnome calendar app but also still have thunderbird setup to handle calendar links. Or evince (akin to preview.app) doesn't support drag/drop editing of pages so I have to also install 'pdf arranger' to do this.
I think there's a chaos tolerance one has to have in approaching linux, which is fine! On the plus side I've really appreciated hearing quickly from developers when filing bugs.
For anyone curious, I keep track of cross-platform workflows here: https://docs.google.com/spreadsheets/d/148zTJUwfVv9xfDcpSoH3...