If both are fact then why is this thread even a thing?
Because even though both are facts, there are those that reject one and accept the other.
But what about the valve? There would be no need for the valve until the psi was enough to harm the animal. But if the psi was enough to kill the animal, it would not have time to adapt then pass this genetic adaption on to the next generaration.
"Darwin answered this claim in 1868 (206). The claim assumes that "gradually" must mean "one at a time." Not so. The different features could have (and almost certainly would have) evolved both simultaneously and gradually. Partial valves would have been useful for reducing blood pressure to a degree. An intermediate heart would have produced enough pressure for a shorter neck. A smaller net of blood vessels in the head could have handled the lesser pressure. As longer necks were selected for, all of the other components would have been modified bit by bit as well. In other words, for each inch that the neck grew, the giraffe's physiology would have evolved to support such growth before the next inch of neck growth."
CB325: Giraffe neck and blood pressure