> So even if the random number generator does loop back around, it still won't ever generate the same GUID/UUID even on the same hardware, and on other hardware

> So even if the random number generator does loop back around, it still won't ever generate the same GUID/UUID even on the same hardware, and on other hardware it is more unlikely yet still (due to MAC address). True, but in crypto that's not the only thing you care about. Usually you want random numbers that are both hard to replicate and, and this was missing, hard to predict. MAC & and timestamp do nothing to reduce the predictability of the RNG. Also, going back to the speed debate: There are usecases where you don't care about these aspects at all and the cited perlin noise, often used in graphics, is one of them. If anything I probably want the noise to be predictable so my preview in Cinema 4D or whatever looks exactly like the rendered result. Stuff gets dangerous when implementors ignore the tradeoffs and want to make things go fast without knowing the implications.