These kinds of objections are predicated on the idea that white space is inherently wasteful.
But the real question is, why is it good to strain the eyes darting them across distances that large. What is gained by filling in the white space just to fill it?
I find shorter lines difficult to read, they require so much more eye movement than longer lines. When a site will let me I prefer the whole length of my monitor as the line length. In my experience I can read on my monitor for 12+ hours a day without eye strain.
[1] https://www.sciencedirect.com/science/article/abs/pii/S01602...