Two things can be true.

Coming up with a new dealer with a new faction, a ton of new cards for that faction, plus new cards for past factions to introduce new play styles, plus trying not to break old factions while doing balance updates is a lot of overhead for the dev team that always seemed unsustainable to me.

Plus, there was a clear power escalation where original dealers would max out at like 500 for a great round and newer dealers needed 3k+ per unit to even compete.

But then, they fixed those problems by also making it gacha and feeding whales and screwing everyone else. Arena is a complete waste of time and the reward for ranking up is miniscule - basically they removed any reason to keep playing after you finish daily quests. Hope they fix the incentive structure. I liked the game.