During a Ross Business School alumni luncheon on social impact, an attendee named Chris Johnson compared quality control to social impact: in manufacturing, quality control used to be siloed in its own group, but now it's expected that everyone take responsibility for quality (hence six sigma training across organizations).
Similarly, social impact is moving from its silo in the CSR group to being expected across the organization (sustainability themes in marketing, carbon footprint reduction in operations, etc). Plus, social impact is increasingly being measured and evaluated (compare ISO standards to the currently mixed & evolving field of sustainability measures).