I recently heart Mike Bostock in an interview and he had a few insightful comments that I'd like to capture here.
The first one is where he called Observable a medium for thought as oppose to just code that you feed into a computer for processing. An observable notebook has the code plus all the other chunks of media that facilitate the understanding from other people. You can capture the process, not just the final result.
He also talked about how he finds the browser a good environment for computation. This is a source of controversy. There seems to be two camps in this area: one that wants all the computations to happen in the backend and another one that wants to do the computations in the frontend. In my opinion, for data visualization makes sense to compute things in the browser since we have tons of user interactions that require a quick response time. But for simple web apps, a more server side approach is totally acceptable.