There's a certain level of truth to it, as none of the Android phone makers appear to be able to push for a customized SoC, even the ones with own designs (Samsung) appear to keep a "wall" between mobile and SoC divisions.

This means that relatively easy wins like throwing a lot more cache on high end phone, are unavailable because instead they are just one of the many customers for the SoC with different priorities resulting in a compromise design.