Also it might make it easier to exclude all SRPMS with a single --exclude line in rsync, but this is usually not what mirror admins want. They would rather exclude only the os component and keep the rest. This would be easier and more intuitive if there is a SRPMS directory at the same level of each $basearch for each repository.
And then we get into duplicating the SRPMS, as the SRPMS are the same across the $basearches. Why duplicate?
What do you mean by "SRPMS are the same across the $basearches"?
Warren