I highly doubt that the scientific community "could not work out how to effectively use that many parallel core" given that the gaming community effectively use

I highly doubt that the scientific community "could not work out how to effectively use that many parallel core" given that the gaming community effectively used the SPE cores of the PS3. These cores are considerably more difficult to use as they only have small local memory and have strong alignment constraints. If the phi does not have enough bandwidth to service the cores that would simply mean it is not a parallel architecture.