I dont believe it has anything to do with them being printed first and, in fact, I believe they were printed along side the main set
While Treasure traditionally breaks this noble dragon, it works just as well with a variety of creature synergies, serving as an enabler, a payoff, and a massive threat all at once
In addition, the landfall trigger effects all Birds you control rather than just itself, like most Chocobos
I really like the concept of the Amass Army token, because it is a kind of modal token that can either act as (sometimes repeatable) sacrifice fodder, or go tall, The build-a-voltron aspect of the amass lords is fun, and scratches the same itch as the splicers, but in both cases, having the buffs tied to a separate creature helps smooth out the risk and reward distribution