There is another reason is is meaningless and that is because the opposition we faced in Graham's era is not the same as we are facing now and have been in the last few years - the game has changed considerably. Graham did not have to face Ferguson's manu which, I hate to say, is the strongest team overall for the last 10+ years. Also, the way refereeing is done these days, a lot of the hard play of the Graham squad would have resulted in lots of red cards - again, the comparison is not possible to make for certain.
All you can say is that in Graham's era the team was reasonably successful in the environment of that time and the Invincibles were successful in their era. How Graham would have faired in these times is impossible to be certain.