Those sources are ephemeral, and don't have the same incentive that organizations might have to preserve or archive their work for the future. We basically have

Those sources are ephemeral, and don't have the same incentive that organizations might have to preserve or archive their work for the future. We basically have The Internet Archive as the sole method of archival for those sources, but they only capture a fraction of the material those sources make accessible. If they go under, or if rights-holders have their way with them, then we're left with a Myspace, Geocities or Vine situation where tomes of content will literally be deleted from what's left of the historical record as time goes on.