Because
1) there have been scant specifics on those numbers,
2) the granular details keep changing,
3) “capacity” can mean a great many things to different people.
To that last point, when the GP hears “capacity increase,” they think, “new rides and attractions!” But does a ride that replaced, say, Primeval Whirl increase capacity? They’re down in terms of capacity from where they were. Does a replacement attraction that is more popular and in demand than what it replaced an increase in “capacity,” even though the THRC for both old and new attractions is 1:1? Some would argue they are.
Do exclusive enclaves such as DVC lounges or DVC resorts increase capacity? Some would argue yes.