My ArcGIS Server 10.2.1 is running under a domain account for the server account. I've been asked by the system admin why does the server account need full-control permissions to folders such as <ArcGIS for Server installation directory>\framework or the directories folder. Couldn't it just be given a read/write permission instead?
The installation process gave indeed the necessary permissions to the account.
My SysAdmin just asked me out of curiosity why the account needed such a high-level permission and I couldn't find an ESRI documentation which explains it. I'm guessing the account needs to be able to delete files regardless of file permissions, but I'm not sure.