Not that I'd know: but at some point after the nineties Usenet figured out PAR files too, so you wouldn't quite need all the chunks because NNTP servers would d

Not that I'd know: but at some point after the nineties Usenet figured out PAR files too, so you wouldn't quite need all the chunks because NNTP servers would drop some of them occasionally -- though to your point, yes, every NNTP server would de facto mirror everything.