yes, that is true, current cables won't affect much unless you have a bunch of cables in front of the only fan pushing air in, as is the case of my pc, but since it is a itx pc with a really low tdp cpu, i don't get worried at all by that
anyway, nice cables are a direct reflex of a unhealthy perverted mind, that is why my case looks like a dumpster!
doesn't hurt to do the cable management and only takes a couple minutes, while you do it, you can clean case if it is dirty and detect possible unscrewed screws or cables not fully inserted