Nielsen was mostly concerned with labeling himself a “guru” to boost his consultancy firm. The idea of user-driven design goes all the way back to the late 60s with the rise of Participatory Design.
I never really got the hype around Arc so I see how Dia is already a much more focused product with a more ambitious pitch. That still can't hide the fact that this major pivot is most likely motivated by their investors.
It almost always means bloat though, because any library that’s not updated in the span of a year is considered “abandoned” and succumbs to feature creep.
I’m disappointed in the fact that the main ambition here is only to recreate a browser for the sake of independence. There is so much potential in creating a modern browser that could for instance focus on performance, privacy, access to lower level APIs, etc. rather than carrying the eternal burden of backwards compatibility.