I agree that if the thing you're trying to show is "Here's bounding volumes and intersections in 3D", then the Three usage just cleans up a secondary implementa

I agree that if the thing you're trying to show is "Here's bounding volumes and intersections in 3D", then the Three usage just cleans up a secondary implementation detail. However, it seems to be rare that people will write "Oh, and the drawing part is just for visualization, ignore this code because it's convenient". The problem with the wide spread of Three is that it is some crazy sprawly combination of utility library, engine, and framework, and that it encourages a particular worldview on new graphics programmers that don't have any understanding on how the underlying hardware or math works. It's useful in the hands of somebody that already knows that stuff, but harmful from a pedagogical point of view.