It's all very clumsy and restrictive, and makes rapid, wide access to ABORI articles difficult or impossible. ABORI often printed rejoinders or follow-up articles. So in following a single topic, it's not uncommon to want to read several articles together. This isn't possible if there are more than three (without waiting three weeks).
So, a big cheer for what they've done, but also a request that they remove the existing strait-jacket and make ABORI articles available under the normal JSTOR terms.
Dominik