This paper offers a conceptual review of artificial intelligence (AI) integration in mental health counselling, grounded in a population health perspective. It examines AI as an active force in digital therapy, exploring its ethical, clinical, and systemic implications. Through analysis of global mental health trends, real-world tools like Tess, Woebot, and Wysa, and emerging neurobiological insights, the paper identifies where AI may offer support in care, especially in structured, lower-intensity settings, and where it falls short-particularly in trauma-informed and relational approaches. It also discusses systemic challenges including workforce shortages, underfunding, and medical gatekeeping, alongside policy recommendations for improving access. The paper closes by advocating for ethical safeguards, inclusive design, and collaboration between clinicians, developers, and policymakers to ensure that AI enhances, rather than replaces, the human relationships at the heart of therapy.