Most guru's take an 'all or nothing' approach, this goes beyond programming, look at food-guru's "eat only carbs, never eat refined sugar" etc. This is for me the same as "always do TDD, never use static methods".
People without experience often look at guru's because they can not yet think for themselves.
I'm a developer in my 40s, have done a lot of projects in a lot of different companies. Having this experience gives me intuition about what to do in what situation. I just (think I) know when I should write a unit test and when not.
The 'all or nothing' attitude is created by people who want to be guru's and is followed by people who want to have some guidance.
This is not a bad thing, it takes time to shape yourself as a programmer. This takes years: http://www.norvig.com/21-days.html
Learn from the guru's, and be consious, people preaching an 'all or nothing' view of the world are NEVER right :)