The ten year anniversary of Dota's public release is coming up (yes, we're working on some fun stuff for it; no, we're definitely not going to hit the July 9th date listed on Steam). As anniversaries go ten years is a big one, and while looking back is important, what's more important is how we approach the ten years to come.
This seems like the best decision for sustainability. It seemed like real frustration was building up around the battle passes being the only content released (even though everybody kept buying the damned things), and it felt like lots of other stuff was being neglected to churn them out. If Valve wants to keep Dota going strong, it can’t afford to let the game grow stale chasing after whales who are going to keep playing regardless of whether there’s a battle pass or not.