Interesting. I could also imagine that the inverse of that point is also true: if one of the suppliers is really good and reliably so, if Apple depends on them more than the others, the cash inflow will help that one supplier more than the others, which that company could put back into R&D to widen that quality gap. And if one supplier is far superior to the others, then the comparability == competition between suppliers lessens, and so does Apple's bargaining power.