What is the point of J2O?
Getting levels and information about JJ2.

What is the point of the JCF?
Friendly discussion of JJ2 related topics (and the non-jazz related forums, but nothing's perfect)

Are J2O and JCF official sites?
Not at all. They are community created, as were Jazz 2 City/JMMB and Universe Jazz (the two previous main sites). Yes, they are probably the most popular JJ2 sites. That does not mean everyone visits them, nor that they are somehow forced to visit them.
If people try to get you to visit them, it is (usually) because they have what you are looking for, or something you could use.

You are completely free to create your own site. Depending on how you make, numbers of people will probably like it. Here's a hint - viruses are a No.