But anything can affect a reality. If an AU world sacrifice itself or not. If Eli has turned right or left on a corridor. If Rush could translate something or not. If Novus was being destroyed or not. Maybe the MW or P galaxy events haven't had a direct effect on the Destiny, but reality is reality everywhere. So in this case we could have seen such AU versions where the Blueberry occupied the Destiny, when the Ancient have never left, when the CBR is completly solved, when Destiny has gone back to the MW or when Destiny has never left etc.
When I have talked about getting technology : check what happened with our first precious ZPM. There was one AU, where the SG-1 has been lost in Egypt. Then a second AU which also sent the "weird" SG-1 back to Egypt. Then the third AU, which became our prime timeline got a ZPM. But come on, two AUs have sacrificed themselves for this step then the third got a ZPM what they haven't done anything for as they shouldn't know any other details what was recorded on the tape. So this is cheating and not far. Our heroes haven't done anything while they have received a ZPM.
Similar happened in Twin Destinies. Suddenly everybody and everything are duplicated, so they "steal" stuffs from their own AU-Destiny. Or when magically the shuttle returned by the Eden aliens. This is cheating.
Or we could talk about Continuum. Multiply AU were destroyed and then they simply executed Ba'al while they have no idea what other AU heroes have done for them. So I am sure it is fun for actors to play the evil themselves and to show their acting skills in other roles, but it still felt as cheating.