9 months to me is a huge amount of time. I don't want to have to wait years to be super productive. I want to be super productive right now and by using other platforms I can be.
For a new viable web platform to be accepted it needs to really explode in popularity. It has to offer MASSIVE gains.
Look at node, it offers performance and also offers the benefit of using the same language on both ends. That's pretty neat... maybe, but I think you would at least agree with me that node's popularity and growth has been unmatched. Even so, it's still quite far behind rails and I don't think it will catch up.
I'm not some massive rails fan boy either. I only started using it when 4.0 came out because the ease of caching seemed interesting to me and I was looking for an excuse to go from node/express to something more opinionated just to see if it was more productive.