[grandalf]

Correct. It is actually opposed by ruby on rails, which is why when Rails apps get sufficiently large they become difficult to understand/maintain.

One example is overriding an association proxy to have other side effects. Sure it makes for a few very sort lines of code to cause whatever those effects are, but unless someone has read the implementation of the code that behavior becomes completely opaque.

Similarly, acts_as_foo plugins that add implicit behavior everywhere.

The core idea was clever at the time -- that one could do better domain modeling than a few sql statements in a file by using AR and callbacks, but after the app gets a bit complex the domain model classes typically become very tightly coupled and much logic has been flushed away into implicit behaviors to make the remaining code halfway readable.

I have yet to see a Rails app that can stick with the basic structure with over 20 models and still feel remotely well engineered.