If you are a software entrepreneur as opposed to an individual coder, one of the things you have to consider is how easy it is to hire someone who knows the platform or language you've selected. It's a fact that in the US and around the world, PHP developers outnumber Ruby developers by a significant margin, probably at least an order of magnitude.
In some ways, this may seem like an unfair comparison (by way of analogy, pedestrians outnumber drivers around the world as well). This doesn't address whether Ruby is "better" or not than PHP (or Smalltalk, etc.), it only has to do with what a startup engineering manager will have to contend with if an when your startup gets traction and you need to start hiring people at a particular moment in time.
I'm not sure what this means, but I think it reflects an incorrect bias that everyone you ever hire must necessarily be "plug and play". This assumes that humans are not educable which is not the case with the possible exception of certain conservative legislators.