With a 9.69 Johnson would still have been well being Bolt who's done a 9.58
Funny how in light of how many Jamaicans have failed doping tests in the past few years how so few people question a 9.58 compared to Johnson's time. And at championships, including this year's, when his amount of races in the run up to the champs has been meagre, and his times in them, relatively slow, just put his remarkable wins, esp in the 200m with a time he's not done in 5 years, down to his competitive spirit and him being a saviour of the sport. He'd have run even quicker btw in that 200, but he practically stopped running in the last few metres in order to sickeningly showboat to his rivals.
So rather than questioning Schippers who unlike Bolt has been injury free, people should be taking a damn good look at 'the saviour' instead imho. In his defence people could say that Bolt was a known child prodigy, but by the same admission they would then also have to admit that if she was beating boys at school, then so was Marita Koch.
As for the advantage the track gives, many athletes have commented on just how fast the new tracks are and that it is like running on air. And that's borne out in the sheer number of PB's, NR's that have fallen even at the current championships. Therefore a 0.1 of a sec advantage every 100m when compared to a 27 year old (1988) track, is certainly a good starting point, it may even be more than 0.1, however I can't see it being any less.
As for Koch et al, I seriously doubt they were put on drugs while still small kids, and evidence would seem to suggest Marita was beating boys before she was enrolled, plus like I said, no amount of peds is going to give you the ability to be WR fast from 60-400m otherwise all the female GDR athletes would have been exceptional over such a range and Marita would have had far more competition.
She was at one point the 60m WR holder, at one point held the 2nd fastest 100m time (behind Gohr iirc), held the 200m WR, unoficially holds the 300m WR by quite some margin, and ofc is the 400m holder. Over her career, she set (or helped set) 31 WR's, no other runner comes anywhere near that number.
In any era, it can be said that most of the athletes are operating on the 'same level playing field'. However, like Bolt has been for the past 8 years, Marita was still, SO far ahead of the rest though, especially over 400m, that there's a point where it must be admitted that it's just as much down to ability as it is to any peds. It may disappoint a lot of people inc media types who want to diss the former GDR, when athletes of their own nationality were lining up doped to the eyeballs, but without wanting to sound stereotypical, on ability alone, that white woman could sprint like no one has ever sprinted before, or since.