Respect the language
Every programming language lacks some useful features, which other languages may provide. Many experienced programmers know several languages and try to port features and semantics from one language to another. It looks terribly wrong and inconvenient when one tries to write Java in Ruby, as well as vice versa. When you try to make a paper-like layout on the web for a newspaper you are shooting right into your foot and get nothing except buggy quirky page behavior and sleepless nights in fixing css bugs.
When you are trying to invent classes in JavaScript you end up with 10 different (incompatible) implementations with bizarre semantics (“where is the ‘this’?”).
The world is overcomplicated already. Meta programming (building all these frameworks, libraries and DSLs) is meant to extract and polish The Knowledge and minimize future efforts. Instead, we have to learn more and more things over time instead of keeping strong focus relying on our past achievements.
The first rule of thumb for a smart programmer: respect your language, choose appropriate tools for each task. Invent your own tools if you have to, but do not break already existing ones.