I'm sorry but I just don't get this, in your previous comment, you mentioned:

You are more than free to re-implement anything Rails does yourself and release it as a gem. Modularity and flexibility are built right in.

And right here, you also mentioned:

I'm not surprised he found it difficult to actually integrate into Rails. Rails is a framework. You don't treat a framework like a library. It's not going to play nice with your design because frameworks by their very nature impose the design on you.

So which one is correct here?