Earlier quoted context omitted.
There is an active debate on whether immediate full disclosure is the right or the wrong response. In general until there is public disclosure, vendors do not feel motivated to fix problems. Unless you release details, people cannot verify that they are vulnerable. And if an exploit is already circulating among "the bad guys", then you're not doing that much damage by disclosing. In this case it looks like someone is…
That depends on the vendor. Some vendors are slow, some vendors are fast. It is wrong to say that no vendor even fixes bugs unless they are publicly disclosed, it is not what responsible disclosure means.
That said, Apple's track record on this topic is not exactly stellar.