You definitely don't understand how the World Between Worlds works. Pulling someone out of their proper place and time doesn't create a whole new reality; it just changes the relevant circumstances of the specific event being observed and interfered with.
Despite Dave Filoni's public trolling, Ahsoka always survived her duel with Vader, as evidenced by the fact that we almost immediately see her walking deeper into the Malachor temple after the scene cuts away from her and Vader fighting. Ezra pulling her into the World Between Worlds resolved the duel instantly because she was no longer physically inside the temple for Vader to continue fighting, but his actions didn't cause her to survive that fight when she otherwise would have died during it.
Someone pulling Anakin from Palpatine's office wouldn't result in Mace Windu killing Palpatine; it would result in Mace dying without Anakin being involved. Subsequent history would be different insofar as Anakin falling to the Dark Side in that specific moment, but we wouldn't be existing in some alternate reality where his fall never happened; it would just happen differently.
Yes, Ahsoka talks Ezra out of saving Kanan by saying that the Ghost crew wouldn't have survived without his sacrifice, but that's not something she has any way of verifying. Ezra believes her, but that doesn't mean she was correct, and what we actually see depicted onscreen indicates that she wasn't.