Back is for the infoweb
You know how there's this big debate going on about "document web" versus "app web" browsers?
Back is a browser-in-browser. It's built on the "appweb" as a webnative app that runs on any modern browser, no plugins or servers required, as an experimental interface into the "docweb."
So you know, there's a "back to the basics" theme there, all hypertext, no javascript, yes readability parsing, that kind of stuff. Like those read-it-later apps, taken to an extreme.
There is truth to the thought that the modern browser has become so complex that no one except huge companies are able to maintain one, let alone create one from scratch.
Yes, it's an operating system. And if you required every app developer to build their own OS there wouldn't be many.
So I cheat. No need to write my own rendering engine, fork Chromium, or even build an Electron app. Start from text and links, images and such, use modern browsers as a GUI toolkit, and focus on everything around rendering.
Like remembering.