Why?

Moses speaks to the people as one who has intimate knowledge of Yhwh’s nature and purposes. Not only does his prophetic utterance presuppose intimate knowledge of the divine, but Moses’ intercessory prayer also testifies to a deep understanding of Yhwh’s attributes and plan. The intercessor can influence the divine decision-making and rebuke the people with divine authority because he has a “place” at the divine council (cf. Exod 24:2–4, 15–18; Deut 5:27, 31).—Standing in the Breach, page 168