It's all about the nuances of attention again. The secret is quite simple: the less we have to wander with our eyes through the visual space, the happier we are. The numbers are easy to find, don't slip your mind (as you ramble to the next chart), easy to compare with what's a couple of bars to the left.
In addition, if the visualization takes up a lot of space, then along with the useful area of the diagram itself, it also increases the empty space between its elements. And each visual gap is a stop for our focus and attention.
The red line on the picture shows the approximate direction of an eye when viewing the diagram.