The state is constantly changing, to publish events NIP-66 style would be burdensome in its own way. When I considered publishing events for a similar purpose, I backtracked and landed at a DVM as well.
Discussion
What is a DVM anyway?
The request response stuff makes it be seen as something it isn't, or shouldn't be. There are at least two different use cases for DVMs, one is good, the other isn't, and they're mixed together in a cursed mix. The good one doesn't need the request-response interface, the other does.