An autotune doesn't measure how powerful or smooth a bike is, just how much oxygen comes out of the exhaust and makes a "best guess" for how much fuel to use.
But that's where that first Dyno comes in, to determine the values for a smooth/best power delivery, you then set those values in the mapping and the autotune will automatically adjust the mixture to those values, regardless of outside elements influencing A/F mixture
A PC without AT is just a snapshot of taking the best values for A/F -at that specific time -under those specific circumstances, that your bike is being tuned
Which differ the moment you ride away from the tuning center (and just think about Ram Air conditions not being present on a Dyno)
The AT will keep these values consistent regardless of the circumstances
So, for example:
If you have set a 13/1 A/F at 8000rpm, (and 13.3/1 at 8100, 13/1 again at 8200, etc -Also taking throttle position into account)
It doesn't matter after setting up the tuning tables, what the air pressure is, what the temperature of your engine is, if it's wetter, or colder outside, or your filter needs cleaning, or you put in your baffle.
The AT will take the data from the Wideband sensor and when hitting that RPM/Throttle position, (if necessary) adjusts the mixture on the PCV to that 13/1