"Is there anything Rails can do that PHP cannot do? *No.*"
That's not me, it's Derek Sivers of CDBaby (hat tip to Greg Beaver).
Jeff Moore has related and insightful comments.
Update: More wisdom and analysis from Pervasive Code regarding "immature developer attitudes".
Are you stuck with a legacy PHP application? You should buy my book because it gives you a step-by-step guide to improving you codebase, all while keeping it running the whole time.