There is a huge advantage to do that. False flag attacks are one of the tried and true methods of intelligence agencies since ancient times.

For example the official pretext for WWII was started as a false flag: https://en.wikipedia.org/wiki/Gleiwitz_incident US did it at the start of Vietnam War: https://en.wikipedia.org/wiki/Gulf_of_Tonkin_incident

We gain a lot from this. We can for example manufacture "Russian hysteria" - "Look we found a Russian rootkit on a DNC server". We can attack our allies and then make it look like the Chinese did it, and so on. It is immensely useful.