A direct approach usually means the garbler sends the labels for its own inputs to the evaluator, protected by the channel or by a key the evaluator holds. The assurance question is what protects them in transit and what the evaluator can do with a label it has already seen. A direct approach is simpler to audit, which is a real benefit.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.