You can create a mailing list and c/p to everyone, have the email replies go to the list, organize the distribution however you like. The PM in this case wanted it done departmentally.
While holistic, unified reports are a nice ideal I think ego may prevent its success at many levels of production. I was in too many "not your job" environments where designers would get pissy if anyone else dared to comment on matters within their sphere. At the very tiptop levels where Matthew is working maybe the designers have gotten past petty turf wars but at the community theatre level it is sometimes more appropriate to keep the warring factions separated.
The designers who want to read the full report will do so anyhow, and there will always be meta-departmental issues (see: Hell in a Handbag) that require blending sections.