So, it leans heavily on Vietnam for its arguments as it was written before Afghanistan (a fail for the Russians and Allies).
What I'm getting is a combination of two factors in conventional asymmetrical conflict;
1) For the superior force, not winning is basically losing
2) There's a sort of "Overton window" for winning, after which you lose at home, politically.
Vietnam played out at home via television and newspapers. The US tried to avoid that mistake during Iraq-I by massively managing the news media and images. Iraq-I happened on CNN and was carefully scripted. Even now we're only just getting documentary accounts of how it really went over there, things that surprise even those who served.
Putin is trying that. But in the internet age I think it's failing.