I thought that prior to that time, the ApHC allowed outbreeding to MORE breeds:
They were. The decision to be made at the time, dictated by the fact that there was then more than a sufficient population of Appys, was whether to close the registry to all outcrossing or to leave it open to some. The decision, which was bitterly fought, was to leave it open to Arabs, Quarterhorses, and Thoroughbreds.
There was no logical reason for that decision - as I said, there was a sufficient population that the registry could have been closed. The decision that was made was made to insure the maximum number of registrations, generating the maximum revenue. ApHC basically bailed out of the breed business to follow their agenda, which was to become a major registry. They have accomplished that, but sadly at the expense of the breed. Only the dedication of hardline Appy X Appy breeders is keeping the actual breed going - in spite of ApHC's policies. ApHC doesn't know what an Appy is - they can and do register horses with no more than minimal Appy blood as Appys.
The origin of the Appy as you describe it is not relevant. All breeds have origins. Do you think the AQHA should permit outcrossing with all the horses, like mustangs for example, that went into their creation just because they were part of their development? How about Thoroughbreds? Should the JC permit outcrossing with Arabs and/or Arab-like horses that they arose from? How about Morgans? Haffies? Why try to justify outcrossing with Appys and not other breeds? If it is suitable for one, it is suitable for all, and if it is not suitable for one it is not suitable for all.
Appys are a substantially older breed than Quarterhorses, and there is, and has been, a large breeding population - there was no reason in the early 80's, and there is no reason now,m to permit outcrossing.
Perhaps you don't understand the rammifications of outcrossing. By permitting unrestricrted outcrossing with certain breeds, you end up with almost no Appy blood at all...
Take an ApHC registered Appy/QH cross, and cross it with another Quarterhorse. The resulting foal is only 25% Appy, yet is registered by ApHC. Now take that foal and cross it with a Quarterhorse, and the resulting foal is only 12.5% Appy, yet is registered by ApHC. Then another generation - 6.25% Appy - registered as an Appy by ApHC. Then another generation - 3.125% Appy...then another - 1.56 % Appy.
Now, do you think a horse that is 1.5% Appy and 98.5% Quarterhorse is actually an Appy? You are a reasonable person, and I'm sure you don't. But ApHC does, and will register that horse as an Appy...