I think it would be harder to use from the perspective of a new developer trying to learn D3. selectAll already has way too many responsibilities in my opinion, making it totally opaque what d3(...) really does. OTOH I guess it's kind of the same with jQuery(..), since it can do both selectors as well as create new Elements.
D3 is one of those libraries that I really admire from a conceptual point of view, but boy do I wish the API was more newbie-friendly.
It's rather indicative of an API that has room for improvement when you start noticing just how many tutorials, videos and books that have to explain D3.selectAll. "Well, you see — sometimes it doesn't really select anything, instead it does this other thing"
Not to mention the source code. Very sparsely commented.