Like most distributions, Fedora uses binary software packages (RPMs in this case) to manage installed software. These packages are built using complex sets of build dependencies (other software packages), some of which are not explicit dependencies but rather implied through their fixed presence in the standard "buildroots" (chroot environments containing a basic set of packages) used in the Fedora build infrastructure.
All of these build dependencies have to initially come from somewhere. Ordinarily, the build system takes care of managing this, picking up dependencies as required, but in the case of a complete bootstrap there are no pre-built dependencies, so they must be created from scratch. Not only that, but build dependencies must be built using a minimal "bootstrap" configuration that avoids circular source dependencies on packages not built yet, and also provides enough basic functionality to rebuild the full set of dependencies using standard tools.
Currently, there is no convenient way to automatically bootstrap Fedora from scratch. Individual packages lack the level of data that would be required, such as a special set of configuration options sufficient to build a minimal "bootstrap" version of the core packages (free of circular dependencies) that could then be used to rebuild the normal configuration. Fedora is not alone in missing support for automated bootstrap, which is currently being investigated by a number of distributions. One of the problems has been that a full bootstrap remains such a rare event that it is difficult to justify the level of effort required to maintain support for automatically bootstrapping in the future (as opposed to making a large number of package changes for one bootstrap effort). Fedora may well eventually support automated bootstrap (a topic to be fully explored). In the meantime, bootstrapping for ARMv7 involved many successive stages.