Thank you for the reply! I appreciate the philosophy of hiring generally good people and letting them learn new stacks as needed. However, there's also something to be said for specialization. For example, I work in scientific computing and have never touched Rails. Even though I might be able to learn what you do, I think we'd both probably agree I'm not the right person for it -- so even just those few extra bits of info about Rails make it so much more efficient for both of us.
If you're curious, capable, and intent on improving, we'd love to talk to you about what you might have to offer.