Thanks rfj and Dew for the explanations. I can see how FVIII would not be considered the optimum target , I just wasn't getting the idea that it was an unlikely target altogether.
I can still imagine future scenarios where targeted interventions in the cascade "tree" are made based on individual differences ( determined by rapid biomarker tests , for example ) with a role for many drugs with different MOAs. The idea , it seems to me , would be precise control of the tree and , thus , the coag/anti-coag balance. A choice between a blood clot that destroys your brain and a bleed that destroys your brain ain't much of a choice but , unfortunately , it's one people are making today.