This series was in response to another thread [1] which wanted to make rust mandatory in an upcoming release.
The authors proposal was to instead take the middle ground and use rust as an optional dependency until a later point of time where it becomes mandatory.
The later point of time was decided based on when rust support lands in gcc, which would make things smoother, since platforms which support gcc would also be included.
Even now, the contrast between repository sizes is wide. Most repos contain 1000s of references, which while not the best to run O(N^2) algorithm, is still okay. But as a Git forge, you also see a share of repositories which contain millions of references.
The authors proposal was to instead take the middle ground and use rust as an optional dependency until a later point of time where it becomes mandatory.
The later point of time was decided based on when rust support lands in gcc, which would make things smoother, since platforms which support gcc would also be included.
[1]: https://lore.kernel.org/git/pull.1980.git.git.1752784344.git...