At least in Dark Fate, they acknowledge that the events of T2 DID erase Skynet from existence, which meant John was no longer the leader of the resistance and another company called Legion did something similar to Skynet and Judgment Day still happened but in a different way and someone else (Dani) became the savior of humanity. But the events of T2 did significantly alter the original timeline.
In Terminator 3 it seems like the EXACT same thing that was originally foretold in Terminator 1 still happened with the exact same company in the exact same way, just 6 years later. ---