Yes, this is exactly the point. They all suffer from condensation but an inner tent provides a barrier between the occupant and the moisture. Do you think that the void between the inner tent and the fly is cooler than the inner tent and warmer than the outside thus acting as a barrier lessening the contrast between the temperature on the inside of the inner tent and the outside air? If so then it might help to actually prevent the amount of condensation overall as well as making it easier to live with? Just a thought.
the inner is almost certainly warmer than the void between the two canvases.
But the inner will almost certainly have a higher humidity level.
Assuming that the inner is a breathable fabric, condensation should only form on the outer.
This may be part of the thinking behind mesh inners. They also give you a physical barrier and a visual warning.
Larger tents should give you less condensation as the ratio between water vapour generation i.e breathing, and air changes i.e drafts, along with larger volume, all work in the right direction.
Condensation in modern housing is an issue, especially timber framed housing. Back in the 70s and 80s, most UK TF housing was done to an American, or Scandinavian spec. This did not work well as the RH levels in the UK are higher, as are the mean temperatures.
It is cured by putting a vapour barrier on the inside and then mechanically controlling the humidity with MVHR.
One of the reasons I think there is room for improvement with tents.