The rise of the phrase “web platform” over the past few years makes me very happy.
Fortunately, the W3C and a group of stewards came up with a term that re-centers the conversation. WebPlatform.org gets it right: this set of tools is indeed the Web Platform. The components have separate identities, but they come together to define a common foundation for more and more applications. The core list on the docs page is the core list of technologies people need to build web applications, whether they run in a browser over the Internet or within a local setup that installs and runs like a regular application.
There are still boundary questions, of course. I could nominate a few technologies that aren’t covered in depth here, and I suspect that folks working on RESTful API approaches might also have a good claim on the phrase Web Platform. I’m also intrigued by “The Modern Web”, a different description appendTo uses for their newsletter. That feels to me like it includes recent practice as well as a great collection of tools.
If you’re building applications – whether they run locally or over a network – consider building them with the Web Platform. If you’re talking about tools for building applications, treat the Web Platform as a coherent toolkit that works across many different environments.