I have seen no evidence "different worlds" - so either I'm steadfastly here, or... [shrug]

This is specifically why our higher-selves left in the Mandala Effects. To give everyone a little hint that there is something bigger going on here. It is not just people's faulty memory.

I have done a lot of healing which involved changing the past. And it it interesting (terrifying) when other people remember that past that you changed to.