Also one thing I see people confusing. They went and obtained all the stones and Hulk snapped his fingers, that right there sets reality back as if the Thanos snap didn't happen. But past Thanos and the Black Order knew what they were planning and got let through a portal by old Nebula who was pretending to be present day Nebula.
That clears up many of the "plot holes" people are talking about..
In a multiverse or parallel universe, when you go back into the past, you're not going back into your past. You're going to the past of an alternate space/time.
For example, when Nebula killed the 2014 Nebula she should've vanished ad well. But she didnt. Because 2014 Nebula was in an alternate space time.
The Ancient One even, told Banner that if he took the time stone, it may save his reality, but hers would be fukked up so he had to bring it back.l
As it relates to the MCU and how they described it, the infinity stones have to stay in the correct space/time universe. Then there's this scene.
Starts at 9:12
So every time the space stone was used (separately, or with the gauntlet) it affected something else directly or indirectly.
