Instead of spending weeks building a new wall in your house, you spend a week building a new house. With AI mundane problems are solved easily and effectively, giving you time to go bigger.
I've been vibe coding a large project the last couple of days and while it is pure magic, I have little understanding of the actual code (yet!) and the output is probably worse than if a team of Software Engineers spent a few months on it, but I still get to have sane discussions with Mr. Claude Sonnet about software design patterns and code coverage. And like I said: days, not months. My "role" in this project has of course shifted from "developer" to "overseer" or "architect" even, but if I hadn't have a Software Engineering background my LLM would have produced a rather poor result.