In B2B software companies, engineering and sales are the only truly critical functions because they directly build and sell the product. All other roles, including product management, design, and marketing, exist to support these two core teams. This reality has important implications: non-engineering/sales teams must recognize their supporting role and prioritize these functions' needs, sales and engineering leaders face intense pressure to continuously improve or risk replacement, and adjacent roles should deeply understand these disciplines to be effective. The prominence of engineering and sales explains why tech CEOs often come from these backgrounds, why product-led growth can succeed by eliminating sales risk, and why investors like Y Combinator require engineering expertise on founding teams.