> You cannot have one person do both of these things.

Isn't that basically what Apple does with their "DRI" concept? One individual directly responsible for the whole project, both for the technical implementation and the product/market fit. This avoids the lengthy back-and-forth negotiation between the tech owner and the product owner about what the user wants vs. what can be done, and also avoids the usual "Wait, I though you were the owner of that?" discussions that we've all seen happen when things get complex and ambiguous.

1: https://mentorphile.com/2019/03/05/fostering-apples-culture-...