Yeah I pulled out d3 for a project recently, having used it before–quite a bit at one point–but not for several years. I just wanted to browse some basic examples for the current version, to refresh my memory and familiarize myself with the current API, but the reliance on Observable drove me up the wall. Even a lot of the old examples from bl.ocks.org just redirect to Observable now.
The presentation is one more layer to understand between "here's the code" and "here's what the code produces". I do generally like the notebook format for exploratory data work, but it's not at all ideal as part of a workflow for writing code that will fit into a larger application, in my experience.