I could be wrong (I frequently am), but I don't think the DA thing was started with Ray. My understanding is that they declared associating with a DF'd person was grounds for DFing, and then retroactively applied that to him, after he was seen eating lunch with his boss, who was DF'd.
I have heard that the usage of DA really started with one Michael Jackson, when he finally had enough of the cheese and cracker men trying to tell him what he could and couldn't do as the King of Pop. He probably did not want to be DF'd, and he probably had a little more clout than the regular JW pulled into the library. So the DA thing was cooked up as a way of him exiting, kinda like a no-fault divorce.
Over time, though the use of DA has grown. As more and more JWs have begun questioning the org, many of them have used a DA letter as a way to exit the organization in a more dignified manner, "you can't fire me, I quit!" And it is being used now for politically sensitive areas like voting and blood transfusions. They simply say the person has voluntarily, by their actions, chosen to disassociate themselves.
No Apologies