Sorry for my ignorance - but what is the gain of having either Gitosis or Gitolite.
I have a Synology NAS server running, but could I not just create a "bare" on any folder on the NAS?
Regards
Main reason is access control. Git doesn't support any access control functionalities beyond repo-level access, and quite often something more fine-grained is needed, such as access groups, folder/file/branch/tag-level control etc.
You don't strictly need it for a lot of projects. However, for some, this is an absolute must.
See my answer about "authentication and authorization": a DVCS (Distributed VCS) has none.
You will couple that authorization mechanism with authentication ones, using ssh or httpd.