Itll even work on nonbasic lands, too
Forcing an opponent to pay life to stop you from looping some kind of trigger on a one-drop is great, and Athreos really rewards building decks that can do that since the opponent might otherwise be able to merely ignore your small creatures rather than having to try to kill them
Unlike videogames, which sometimes are structured in such a way that exclusion is built into the design, Wizards of the Coast employees have repeatedly demonstrated their commitment to fostering a welcoming community
A reimagined underground Hollow Earth concept, remade specifically for the plane of Ixalan
Read More: What is Prowess in MTG
Sometimes this is done for flavour reasons (they needed a certain effect at a certain mana level, but the original printing doesn't work for a plane where, say, the Llanowar Forest does not exist)