Raw number of developers doesn't matter at all. The ratio of offers to developers out there determines how easy the hiring actually is. I've tried to hire some quality PHP developers and it's as hard as Ruby/Python if not harder. First thing is, that you always get all the Wordpress people, who fixed one plugin and claim to have 10 years of PHP experience. Then you have to filter out all the 10 YoE who actually have 1 YoE done 10 times. For some reason all this is less of a problem in less popular stacks.