A substantial portion of software engineering -- and the fundamental jobs of a proper Product Owner and UX Designer -- is to turn "vague ideas about what we need to do" into "this widget, on this page, it should work like this"

It's not a pipeline, it's an ongoing conversation within any functional team, but this requires buy-in from management, who is often selected for "line must go up this quarter no matter the cost" over "hey, wouldn't it be cool if this company was still a going concern in twenty years?"