Why Software Rewrites Never Deliver the Clean Slate Engineers Imagine

A widely shared engineering perspective argues that system rewrites rarely achieve the fresh start teams expect, because organizational memory, business logic, and user workflows cannot be erased along with old code. The piece contends that legacy systems are complex not due to poor engineering but because of years of accumulated customer requirements, regulatory demands, and hard-won edge-case discoveries. A rewrite forces teams to rediscover those same constraints from scratch, often through production failures and escalations rather than documentation. User behavior, sales processes, and support runbooks built around the old system also pressure the new one to eventually mirror what it replaced. The author concludes that successful rewrites are best understood as translations of the past rather than escapes from it.