The point is until the seed IS up it can't preform photosynthesis.
Stage One: Germination
Conditions are met for the seed to germinate. Those conditions are the appropriate heat and dampness. The outer hull is softened, the embyro is activated, and the radicle emerges.
Stage Two: Establishment
The effects of gravitropism on hormones within the seed produce a curve in root growth. Which produces an arch needed to break the soil. The radicle begins growing down in the direction of gravity, "positive gravitropism". Once the radicle has pentrated deep enough to anchor the plant, the arch begins growing upward, producing leverage like a crowbar to break the soil. If this attempt fails the arch begins the process over again until sucessful or exhausted.
Stage Three: Emergence
The hypocotyl arch has broken the soil and begins the straighten itself. The cotyledons begin pulling themselves from the seed, which if oriented tip up, is position to slide off like a sock or condom. If position down the root must fight the downward force of gravity as well as the opposing position of a "closed" hull.
Stage Four: Seedling
The hypocotyl arch is fully extended, hopefully with the hull removed. If not the last remaining energy goes to swelling the cotyledons until successful or exhausted. No cotyledons, No photosynthesis, Dead plant.