Yeah you can say that - the browser environment with DOM and other Wep API's is a framework for client-side apps. Single-page application frameworks like Angular, React etc. are frameworks on top of this, which provide higer-level abstractions and tools. Whether you need these higher level abstractions depend on your use case.

If you have lots of in-page DOM mutation in response to user interaction or data from the server, a SPA framework might simplify things. For a site like HN with very little in-page DOM mutation it probably isn't worth the complexity.