It's not all screens, a logo needs to work irl. The Pentagram post linked elsewhere on this story shows a couple mock-ups of irl advertising and product branding. Want T-shirts to give away at recruiting events? Your T-shirt supplier will charge more for more colors. Fewer colors also generally make a design easier to replicate freehand, and you want amateurs to be able to easily convey your logo. A special case may be made for the old intersections being easily reproducible in some mediums, but consider non-aerosol paints and things get messy.

Aside from physical constraints, I think there is a general argument to be made for simplicity. If something is more complex, there should be a reason for it. Otherwise, toss out the complexity. What is the reason for having more colors? There are other ways to convey overlapping lines, and I would argue that some of them are less complex, though it would be a lengthy argument -- it isn't exactly obvious how the complexity of an additional shape can be measured against the complexity of an additional color, and you can ultimately just subjectively weight one of those factors heavier than other and come up with a different answer. But I think the general case for fewer colors being less complex is pretty sound.

[Edit for grammar]