Relying on platform-reported Return on Ad Spend (ROAS) from branded Pay-Per-Click (PPC) campaigns often masks severe traffic cannibalization. By measuring true incrementality through controlled testing, small and medium enterprises (SMEs) in 2026 can reallocate non-incremental ad spend into compounding non-branded Search Engine Optimization (SEO) and Generative Engine Optimization (GEO) assets that drive long-term customer acquisition.