Even in limited instances we've had teleportation (Big Mountain, The Institute)
? Are those things in bethesda games? It's not fallout universe then. And the special encounter in Fallout 2, providing you actually have 9 or 10 luck, was never meant to be taken for real.
Anyway, time travel or alternate reality seem to be a damn big fat obvious wriiter's rope since a while now.
You don't know what to do anymore? The characters have reached a state where even you are not sure about what should happen next? You would wish the world and people to become upside down overnight, just like that?
You have just been given a world, characters and story that just aren't yours at all, but ended up on your table after some shady business practices of your company, and even if naturally you call yourself a fan and are very exited, deep down you just want to change everything?
Look no further, science-fiction concepts of time traveling and/or alternate reality vaguely based on relativity's theory are there to solve all your problems while keeping the illusion that what you are doing is still the same universe/characters ect...
I like Come back to the future movies as much as most, and in my opinion, the Lost series actually handled the concept of time travelling pretty well in season 5, because of the 'whatever happened, happened, you can't change the past' direction.
But in truth, good handling of it is so rare and tend to become a very bad rope:
'Let's break all the rules and all the world/characters evolutions that we or or others worked very hard to reach in the past years and let's do whatever we want because now we can.'
Time traveling and alternate reality should be banned from any story telling because of this.
And though it's not the same impact on the world, amnesia's ropes also should be banned now.
Amnesia worked well enough in Planescape Torment though it wasn't so necessary in my opinion, however the old rope is very dubious in the witcher, and I am being nice there.