That is indeed true. There do seem to be a couple of patterns however:
First, people with any form of financing don't seem to be getting letters. A small handful have, but the rest are still waiting. There is no real explanation as to why this is the case.
For people with no financing, and who have had their docs approved, we now have over half reporting that they have gotten their offer email.
There are people who had their docs originally approved right out of the gate, and they are still waiting for their offer letters. Possibly due to a shortage of Ambassadors? No idea - VW isn't saying.
And then there is the question of people who bought after 9/18/2015. There aren't many, but they aren't getting anywhere either.