It is not the argument that the DNC was so secure that only Russia could have owned it up. Literally nobody thinks that. Everyone agrees the DNC's security was comical.
The problem for Russia skeptics is that as easy as it was to own up the DNC, it is in fact very difficult to own it up in a way that points a finger back to Russia, because the "finger" in this case is a collection of IOCs forensically taken from previous attacks that are in most cases known only to law enforcement and to a few very reputable attribution firms.
The problem for Russia skeptics is that as easy as it was to own up the DNC, it is in fact very difficult to own it up in a way that points a finger back to Russia, because the "finger" in this case is a collection of IOCs forensically taken from previous attacks that are in most cases known only to law enforcement and to a few very reputable attribution firms.