From this article, an interview with Fedora’s project leader:
On the other hand, the long-term distributions work by basically not making changes. Fedora doesn’t follow that, your packages will get updated. We try to make it so that major breaking changes happen on releases rather than just as updates. But sometimes, if there is a security problem, we will put out a newer version of something. So for that kind of stable, it is much less so."
That’s why Fedora users are stuck with e.g. the older GNOME version until the next release.
The difference between Fedora and Debian regarding stability is that there’s a new Fedora release every 6 months, while on Debian you have to wait like 2 (?) years for major updates.
That’s how I always interpreted the term “leading edge”.