I've used NZBs that were 3+ years old and they've mostly worked fine. Occasionally blocks are missing, which of course is more likely the older an NZB gets, but most of the catalog is still together.

They're right that many providers are getting hit with notices, which causes them to remove a few chunks of each rar from their server making it impossible to complete the download and too pervasive for repair by typically-sized parity file, but this can be circumvented by using a lesser-known news server as a backup; you still use Astraweb or Giganews for 99% of the transfer, but your fallback picks up the pieces that have been DMCA'd out of AW/GN/another major carrier.

I would be happy to see a more intelligent splitting system than rars, as one missing block in a couple of rars will often make it really difficult to extract the content you DO have and use a more robust delivery system, like a torrent, to download the blocks you're missing. This is going to become increasingly important.

News servers are interesting because they really are a non-optimal method for this kind of transfer that has incidentally become a hot bed for filesharers, probably just because of the plausible deniability ("yes officer, of course we only intend our server to be used by those discussing photography..."). I too wonder if it's not time for a new protocol, something more direct than torrents (webseeds kinda works here, but not quite what I'm looking for) but less hacked-up than NZBs and ASCII-encoded binaries in split files.

It's time to stop skirting around the issue and try to put together a serious underground analog to direct-downloaded binaries, something hearty and immune, or as immune as possible, to interference and foul play like this.