could it be that big portals are being developed by experienced professionals usually - who usually know Zend well and - why to use Codeigniter for big portals when you are experienced with Zend ..
Well define experienced. I have 10 years of PHP experience. Does that make me experienced? I know a lot of students who just finished college and their heads are filled with Design Patterns and OOP paradigms. Are they experienced? Is the guy who has been programming for 20+ years in Fortran, Cobol and C and decides to learn this ‘new thing’ called PHP experienced?
Programming is, to me at least, an art form. While you have many mediocre artists, there are only few who truly are amazing. Obviously there are a lot of artists who no one understands, or rather, no one likes and there is a large group who are plainly rubbish. But all of them have experience.
So what does this tell you? Like I stated earlier, it’s all ‘just’ PHP. Put it in the hands of a truly amazing programmer, and it powers sites like Youtube, Digg and more than half the alexa top 100 sites. Put it in the hands of mediocre programmers, you’ll get the standard corporate website. Put it in the hands of hobbyist, you end up with Wordpress, Joomla and all the other behemoths OS engines. (I’m not saying they are bad products, but if you look at the code, most good programmers would start crying or jump of a cliff).
Obviously you care more about the differences between CI and Zend. I would reckon that most programmers who want to use many of the Zend components, are inclined to just use the whole package, instead of adapting components to CI. This would make sense, especially if they have a lot of experience with the Zend framework and are comfortable/familiar with the conventions/configurations of Zend.