Yeah but if it really didn't serve much of a purpose, you wouldn't see case manufacturers redesigning their cases to facilitate it better now would you? It's more than just a selling point.
The way I see it, since less cable clutter at the very least encourages regular cleaning, something even cable management skeptics here have agreed on, it's highly likely users paying attention to cable management would also be less likely to errantly wire something, or through neglect of cleaning, cause a component to fail. So yeah, it makes sense that case manufacturers would make their cases easy to route cables with appropriately placed holes and cable protecting grommets (which also make it easier to pull cables through them). It's something that would garner praise from both users and component manufacturers. Sometimes when users refuse to do something, they're really just wishing the manufacturers would make the process easier....but the "otherwise manufacturers wouldn't do it" route isn't that convincing of one. I've seen manufacturers do all sorts of things that ultimately didn't serve much of a purpose...
With laptops you have a worse problem IMO, not being able to do much about performance or temp issues.To avoid the hassle, I just bought a laptop, but I also tried to hide the cables on my old computer, only I realized that it is better to do, in special cases, for more convenient sorting of cables.