In Vanilla WoW terms, the difficulty we're talking about should roughly be the same as the difficulty in putting together a 5-man group for Blackrock Depths, Lower Blackrock Spire, Scholomance, Stratholme or Dire Maul, the five main L60 dungeons; it's only one extra person, and if you're going for some of the tougher or lengthier options within those, I suspect the logistical challenges are much the same.
This is the thing that strikes me most: Despite this being termed a raid, we're not really talking Vanilla WoW *raid* logistical challenge, we're talking Vanilla WoW *dungeon* logistical challenge. That's a very different kettle of fish. And while matchmaking would absolutely solve that problem, I think it should also be solvable with the tools WoW had back then: communication with a friendly guild or chat in the hubs.
I think that is the biggest barrier to this content in Destiny terms at the moment. If you can't solve the logistical problems to making this happen with the communication tools available to you within the game environment, the communication tools available to you within the game environment are inadequate.