The zone limits were not introduced in AW3, it was already a feature in the game long before that. I don't recall them being in AW DOS but the zone limits were in AW4W when the map was static and country rotation wasn't implemented yet (that wasn't until AW3) and bases were only numbers (named bases appeared in AW3). VoD was, IIRC, B85 and A83 and that is where the majority of the fights took place (with the exception of factory and main base raids) and where the majority of the players were on the RR small ETO maps. The zone limits didn't stop the horde at VoD, all it did was make players up from a nearby base and take the longer flight to VoD and then get shot down and hope a slot opened up at B85 (or A83 if you were an Azlander) so you didn't have to fly so far to the fight. As a die-hard Czlander, my squadron often had to up from C83 and then fly across half the map if we wanted to fight as the majority of Az and Bzlanders were in VoD furballing.
ack-ack
I have to admit that even as I was typing I was wondering if it was during the ever so brief period of "AW2" after AW4W that the base limit was used. I remember going FR during AW3 beta (Big PAC).
I am sure that during this period prior AW3, base names (Jennifer, Grey Eagle, Moggy etc)were introduced along with rotation, Multi field capture and possibly as you say base limits.
I suppose I could check this chronology with the Bigweek crowd.
I have distinct memories of launching from fields south of the river as a Cz and having to modify mission waypoints to merge from different bases because the field had been bombed and the base limit reduced below squadron strength.
So it could have been in RR during this period that I recall. However having said that I would repeat that base limit worked to spread combat.... And if you are correct re the timing then I would state that it worked in RR just prior to AW3..... Albeit my experience is Euro time zone related where numbers were not as great as US time zones.
Further it is still the only measure I have seen that breaks/ modifies the tendancy to horde.