I'm actually surprised that there wasn't a fork of the last GPLv2 release.
The benefit of starting over is that Landley was able to relicense Toybox as BSD, after he first released it as GPLv2. That would not have been possible with a fork.
If this were commercial software, he would have been forced to "cleanroom" the new code.
Toybox is used on Android to implement a number of POSIX.2 utilities.
https://en.wikipedia.org/wiki/BusyBox#Controversy_over_Toybo...