I doubt the single global ordering is as important as the author suggests. If nothing is in practice delayed for more than a short period, then either ordering-

I doubt the single global ordering is as important as the author suggests. If nothing is in practice delayed for more than a short period, then either ordering-by-arrival or ordering-by-declared-time-with-'seen'-indicator both mostly work. It's whatever you get used to. And I've seen all sorts of micro-failures in Twitter's provision of global ordering: gaps in my display timeline in one client but not others; tweets seeming to appear below the 'topmost' position when revisiting the stream; difficulty reloading recent history that was already local at one point. A distributed/federated system might be a little fuzzier on some ordering behaviors... but make up for that in other dimensions.