Why use MERN for MVP development?

Three reasons. First, MERN's single-language architecture means a 2-engineer team does what takes 4 in a mixed-stack environment. For a founder on a fixed runway, that matters. Second, MongoDB's document model handles the schema changes that happen every sprint in an early product without migrations. Third, React with Next.js handles both the marketing site and the authenticated application in one codebase. One team, one language, one deployment pipeline.