I worked at GOV.UK for a few years on what was effectively specialised CMSs all written in Rails. Mostly basic CRUD stuff. A contractor came along and built the most insane CMS I've ever seen. I found out later it was flavor of the Java Repository Pattern using dependency injection. It became so difficult to work with that the last thing I worked on there was to delete it and rebuild it using standard Rails patterns.

The KISS philosophy exists for a reason and that includes over-using advanced language features just to show off.