I had a look at this the other day - of the new flats behind the South Stand, only one of them is quite close to the back wall and that is in the corner near the Y section/ floodlight.
Apart from that, it would seem to be a ground with the luxury of a significant amount of space - particularly, if as has been suggested, the new housing plans for the area involve changing what is currently the section of Pittodrie St behind the Main Stand.
The stuff on Pittodrie coming from the club is purely due to the financial imperative to sell the land to help fund the new place - and nothing to do with it being impossible to rebuild a modern fit for purpose ground on that site.