I finally understand why DDD exists (and it took a painful codebase to teach me)

For the longest time, Domain-Driven Design felt like something senior engineers talked about in conference talks but nobody actually used in real projects. Terms like "aggregate root," "bounded context," and "ubiquitous language" sounded like they were pulled out of an enterprise Java textbook from 2004. I kept nodding along in meetings and Googling things quietly afterward. Just vibes, honestly. Then I inherited a codebase where a single UserService file was 1,400 lines long. It handled authent