Well, that is implied by the title: "Plywood: A New [...] Framework". Frameworks are by definition about providing the core elements to build your stuff on top of them[0].
It has been my experience that most software posted on HN has little description of what it does, and no description of why it exists. The parent comment was highlighting the excellently concise mission statement written on the first page. I wish every project would do as well.
The word "framework" by itself provides no indication of how specialized the tool is, or what problem(s) it aims to solve.
The above description indicates that it is a very general-purpose framework (handling things as disparate as game engines and web servers) and that it aims to enable code reuse, not just eliminate boilerplate code.
Eh, no, that description doesn't do that, a better description is what is above it because it actually mentions what it does and provides. The part quoted in the message i replied is largely implied by the word "framework". Of course it isn't a bad thing to be explicit (especially since some people may think that framework is just another word for library), however it isn't any clear about what the framework does.
For example think of MFC: you know what that framework is all about (Windows GUI applications), yet the description could easily fit with MFC (and indeed all of the above have been implemented on top of it).
[0] https://en.wikipedia.org/wiki/Software_framework