After 25 years building platforms first, veteran argues it's wrong for AI era

A developer with 25 years of experience argues that building horizontal platform architectures before features is outdated in the age of AI agents. McKinsey data shows 88% of organizations use AI but only 6% see bottom-line impact, partly because agents struggle with large, unbounded codebases. The solution is vertical slices—organizing code by feature—which give agents small, clear scopes and enable overnight feature delivery.