Rotation mechanism for new players and also a disincentive to purchase cards and packs of cards from new collections.
I love Splinterlands, I've always played manually too. I share the same idea, I myself had the crazy desire to buy cards for my collection especially Untamed, but with the rotation of these cards I sold at a loss and today it's very difficult for me to buy cards. Precisely for this reason of card rotation.
You've described the problem very well, the main problem is really the lack of in-game use cases for old cards because you either give them to a bots or you sell them and in a card game as beautiful as Splinterlands this is in my opinion a mistake
!ALIVE
!PIZZA