I noticed that on the touring bike frame sizing link below that on all sizes of rider/frame size from XS to XXL, that the chain-stay lengths are all the same at 425 mm. Also the seat tube and head tube angles are all pretty close.
This makes me think that CS length, seat tube length and stand over height, are the most important as i'm guessing chain-stay to seat tube angles are also pretty similar across the board?
https://www.backroads.com/why/great_...ng-bike-sizing