Because you need a lot engineers (so, hefty amount of money) to clone that concept? Basically CentOS concept is "freeze the version of all the packages and supp

Because you need a lot engineers (so, hefty amount of money) to clone that concept? Basically CentOS concept is "freeze the version of all the packages and support them 10 years". But in real world people need new features, new bug-fixes, i.e. new versions. If you want to commit to that "never update" policy, you had to back-port everything people wants. In short, forking it is easy, but keep it attractive is not.