I think Twitter Bootstrap and Zurb Foundation are trying to bring some of that consistency back into the Web. Even completely unique applications with their own design and functionality are easy to navigate when they start with these frameworks.
For example, Roll20 [http://roll20.net/], an online RPG tabletop, is a full-featured web app that is easy to use even though it's quite complex, partly because they worried about designing a custom UI on the macro scale, leaving the micro scale (buttons, form elements, etc.) to Twitter Bootstrap.
I totally agree. The whole idea of responsive design that those types of frameworks promote is exactly the type of defacto standards that arise out of the mishmash of web UI/UX.
For example, Roll20 [http://roll20.net/], an online RPG tabletop, is a full-featured web app that is easy to use even though it's quite complex, partly because they worried about designing a custom UI on the macro scale, leaving the micro scale (buttons, form elements, etc.) to Twitter Bootstrap.