"[S]omewhat arbitrary" is a correct description. We take something that is fundamentally partially ordered (real-world events that may happen exactly at the same time), respect the partial order and extend it to a total order. The extension is arbitrary, but I fail to see the problem with that, or how it contradict anything we wrote?

Could you explain what bounds you are interested in and in what way you think anything is exaggerated? I would like to update the docs if necessary.