Every handover loses something. The person who talked to users writes a brief for a designer, who writes a spec for an engineer, and at each step a little of the original understanding leaks out. By the time anything ships, the problem that started the work has gone blurry.

End-to-end work is the alternative: the same people carry a problem from observation through design and into what gets built, without passing it between roles. Big teams traded that continuity for scale. Specialise, divide, hand off. For anything large, it was the only way.

AI changes the math. Someone who knows the work, or is building directly with someone who lives it, can now design the solution and build it themselves, holding the whole problem in their head the entire time. End-to-end isn't doing every task yourself for control. It's refusing to let the original problem get lost as the work changes hands. Continuity used to be the thing you gave up to work at scale. It isn't anymore.