It's pretty trivial to get an ORM standing up in a non-rails environment. Sequel does a great job of this by including bin/sequel so you can run commands like '

It's pretty trivial to get an ORM standing up in a non-rails environment. Sequel does a great job of this by including bin/sequel so you can run commands like 'sequel migrate' and it just works. There's no reason AR couldn't have it's own bin to manage migrations and model generation so that it not stuck inside of the Rails Rakefile kitchen sink. All the other stuff you speak of falls in the same category. It's all great code/libs, they just need a CLI so they're not stuck in the monolithic Rails Rakefile. The good news about Rails 3 is that it fully embraces Rack, so the plugin ecosystem you speak of is much more portable these days if you want to run it in a different framework (I'm thinking of libs like OmniAuth, etc) Alas, I would never recommend an architecture on the merits alone that you can "swap out the backend". That doesn't really add that much value to end users and never really happens quickly or easily in the real world. The benefit I describe in the blog post to the view layouts and logic being separate is that you get an epic win on the content delivery side of the house. This is a huge deal for mobile web apps.