However, Rails is just too fng complex. It's true what they're saying, Rails-only programmers aren't necessarily Ruby programmers. For a good reason, even the simplest tasks are performed with Rails metaprogramming magic behind the scenes. Idiomatic Rails programming actually means not doing imperative programming which sucks. Programmers want to actually know and control what they are doing.
I once dealt with a legacy Rails app that had really complex Models. ("Fat models, thin controllers") Of course the original designers hadn't thought about every corner case, and of course not thought about what AR is actually able to deal with seriously. The app was just slow and not maintainable.
But to say something good about Rails: creating standard web pages with it is a peace of cake. All standard tasks are automatized.
Great when building but it sucks when debugging and maintaining.