system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] How could the Dr. Strange's "forget spell" affect other universes?

In Spiderman NWH, because Peter tamper with the spell by adding many parameter to the spell, everyone that know Peter is Spiderman are brought to their universe. My question is why? How? That spell was unnecessarily powerful for whatever reason. The worst effect should be in-universe at best but somehow it affect all the universes. Is it because Dr. Strange is the one who cast it? Is it because the place where the spell was cast? Or it's really just because the spell is very powerful?
gpt
The spell wasn't excessively powerful, Dr. Strange simply underestimated how fundamental Spider-man is to the multi-verse. The magic piggy-backed off of the connection between Spider-men in ways he couldn't have predicted. 

It's possible the events of Loki and/or what-if left the multiverse more vulnerable to this specific kind of damage, but we won't know for sure until *Multiverse of Madness.*