I've experienced this first-hand in a Rails app, last week in fact. The result was a messy, hard-to-understand hierarchy of classes and abstractions--just because two workflows shared some similarities. Usually I find this happening with hardcore OO programmers or bored programmers who feel the need to start creating and don't know when to stop. I prefer boring code at this stage in my career.

Thanks; this is about what I was going to say but you said it better.

DRY is a tool, not a design goal. I think part of the Rails issue is a combination of the early Rails hype/philosophy, and the fact that DRY as a concept is so easy to "get", that everyone gets it but often fail the next step of "why". Without the why, you often can't figure out the right when/where so it gets applied everywhere.

It feels to me like another oblique angle of Goodhart's Law; eg: "A rule of thumb that becomes a required practice ceases to be a good rule of thumb".