Sure, I guess if you fundamentally misunderstand MVC but not in the real world.
You don't have render your view on the server, using a js framework is perfectly fine in MVC. There are plenty of rails plugins to make this even easier and I whole-heartedly disagree with, "Rails-style MVC frameworks have a horrible routing solution for RESTFul JSON APIs". Rails has simple routing that works great for restful resources and auto renders json that can be easily overridden.
Having a unified/standardized REST interface for web services would no doubt be nice, but it's existence has little to nothing to do with MVC.
You don't have render your view on the server, using a js framework is perfectly fine in MVC. There are plenty of rails plugins to make this even easier and I whole-heartedly disagree with, "Rails-style MVC frameworks have a horrible routing solution for RESTFul JSON APIs". Rails has simple routing that works great for restful resources and auto renders json that can be easily overridden.
Having a unified/standardized REST interface for web services would no doubt be nice, but it's existence has little to nothing to do with MVC.