Rails is great. And of course it isn't and will never be perfect. Obviously the author would love some alternative frameworks, mainly so he can use some more and some less exotic code patterns. Maybe after almost a decade of writing CRUD apps in Rails he is a bit bored? I can't blame him and seeing the Ruby community so focused on basically one framework is a tiny bit sad.
So I definitely see where he is coming from with all this, but truth be told it was never Rails' indent to be a precision instrument. It has been a reliable framework that makes a lot of Developers very happy. A great reliable car for the masses so to speak. But not a Ferrari.