Point 9 (Not Sharing Knowledge) and point 4 (Documenting The Code) are very similar and I've noticed in my 18 years of software development that the first people who leave a company are exactly these kind who are secretive about their code and too lazy to document their code. They may claim to have found a better job and therefore they leave the company, but they leave a mess and I would never hire them again.
The problem is also that documenting code and writing howtos is not forced by the superiors.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.