Agree: flat/relational structure is highly efficient to store, query planning/optimization/scaling become a lot easier, the language is clunky but relational algebra is beautiful, but...
I think pushing multiple joins to what is still a relational database and getting a complex output isn't the worst idea in the world, as a higher-level layer on top of a regular database.
On the other hand, "it needs four queries/RTTs" is not the worst thing in the world. It needn't be the goal of a system to achieve theoretical minimum performance for everything.
Let those who truly have the problem in prod push the first patch.
I think pushing multiple joins to what is still a relational database and getting a complex output isn't the worst idea in the world, as a higher-level layer on top of a regular database.
On the other hand, "it needs four queries/RTTs" is not the worst thing in the world. It needn't be the goal of a system to achieve theoretical minimum performance for everything.
Let those who truly have the problem in prod push the first patch.