Damn right!
And what if the dog hasn't got a collar?
And how many of us have the strength (even if we had the presence of mind) to twist a collar hard enough to choke a dog with that much power and a neck the same size as the average woman's waist?
And how many of us would be able to remain upright under the sheer force of such an attack (even suppose we had a handy wall, as in the illustration)? And frankly, with a dog like that, once you are on the ground you are dead. The chances of getting up again are remote.
I have seen people recommending that you push your fist down the dog's throat to choke it. - (yeah, right) and someone on a previous thread some times ago claimed that her DH had done this when attacked by one of these dogs. I have to admit I was sceptical.
Lifting their back legs off the ground is another "popular" method - it might work with some dogs, but the sheer size and tenacity of these make me doubt it would work here. Also - what if the dog then left its previous victim and attacked you? where would that leave either of you? (In fairness, they tend to fixate on a single victim)
Unless you are SAS, I think you'd be on a hiding to nothing, thought the coat thing might provide enough of a distraction to let you escape if you were quick and could get indoors.