I guess the other point is that, up to now, nobody has asked about creating Collections based on author, so no one has bothered to write the code to support this.
It iseems to me that is likely that some of the recent developments around custom columns and the regex copying of fields might mean that this becomes achievable in a relatively simple manner as a by-product of these developments. We just need to wait for these to come out of beta in the next few weeks to see
