If that were true, it would mean that The Valley hires, on average, lower quality developers than non-Valley employers. Is that what you are suggesting?
I don't think it means "on average", since I do think the average quality of a dev is higher in the Valley is better than elsewhere. However, I am saying that getting hired as a marginal dev is easier in the Valley than elsewhere, since there are not enough warm bodies in that area and Valley companies only seem to be willing to reach outside the area for really good people.
It may be more accurate to say that The Valley has different standards for software development on web & mobile than employers in other regions and in different categories. The quality of a developer depends on the overlap of their skills and the employer's needs; never judge a fish by how well it can climb a tree.