[porker]

How about because CodeIgniter is one of the worst frameworks around, which provides little support for separation of concerns, avoiding spaghetti code and general maintainable programming practices.

I spent the start of 2008 migrating an agency off CodeIgniter - it definitely improved their projects afterwards (developer training helped too, but not as much as a well-designed framework did for code reuse).

What gets me is CodeIgniter is how I was writing PHP code back in 2003-2004, 4 years after picking up the language as a hobby. And people still think writing it like that is a good idea.