Indeed it's not, especially when you bear in mind that they both had their demons but Robbo lived in an era where it was much easier to get away with unprofessional behaviour without being subjected to forensic scrutiny by the press.
Bearing in mind the average age of caftards on here, I always find the discussion about who was the better player a bit pointless. I'm frigging ancient by caftard standards and I can't remember Robson playing with all that much clarity. Feck knows how some of the young 'uns in this thread have come up with such a definitive decision about who was better.
I am unfortunately old enough to have watched Robbo from the Stretford End for many years. I agree with your post though as I have fleeting memories of Law Best and Charlton, not enough to give a genuine opinion of their talents.
Imagine Keane with Scholes passing and goal scoring ability and you have Robson (not as good at passing but close). I also don't think he would have quite the impact on the modern game as it is quicker now and he would not be as effective as a true box to box player.