One good negation is "the value/intrinsic utility of a life is the sum of the values/intrinsic utilities of all the moments/experiences in it, evaluated without reference to their place/context in the life story, except inasmuch as is actually part of that moment/experience".

The "actually" gets traction if people's lives follow narratives that they don't realize as they're happening, but such that certain narratives are more valuable than others; this seems true.

When I think about having children, and I wonder if they'd be happy, overall, I visualize my own childhood and think about ways it could be different; and I think about my adulthood and how my childhood affected it. I don't remember ever thinking about the aging and death of my counterfactual kids; or how the process of senescence and death--which I have no subjective idea about--would affect the total utility of their lifespan.