Because he's seen the harm that can befall people, just for being associated with him. Both MJ and Ned have nearly died multiple times, and MJ still carries the injuries from the final battle.
However, in Spider-Man: No Way Home, as we have seen at the end that after the mind-wipe, MJ or even Ned can remember who Peter Parker is aka Spiderman.
Peter left MJ so that she will stay safe as he knows with him she will always be there to help her risking her own life. Same goes for Ned. There are few more thing here not with Peter but from eyes of marvel.
In the Marvel Comics, Ned was essentially brainwashed into becoming a villain, after the real Hobgoblin, Roderick Kingsley, tricked him through mind control. Ned began to believe that he was Hobgoblin all along, eventually committing crimes while under Kingsley's influence and using the Hobgoblin alias.
On top of being implied by a “lingering sense of recognition” when Peter leaves the donut shop, the fact that MJ is still wearing Peter's broken Black Dahlia necklace at the end of the film seems to confirm she (subconsciously) remembers him.
Many believed that this was how the MCU was going to write MJ and Ned out of Spider-Man 4, especially since they'll be heading to MIT while Peter stays in New York, but producer Amy Pascal has since hinted in an interview with Variety that Zendaya will make an appearance in the film after all.
If Doctor Strange was speaking literally when he said that nobody in "the world" would remember Peter Parker, then - surely! - Nick Fury (the real Nick Fury, who has been on the moon this entire time) still remembers him.
In the end credit of WandaVision Wanda is looking in the multiverse trying to find her kids while being surrender by these ruins. Which means the spell that Doctor Strange cast to make everyone forget Peter Parker would not affect Wanda leaving her to be the only person that remembers Peter Parker.
By referencing No Way Home's multiverse story and the existence of Spider-Man, it can be concluded that Doctor Strange remembers Spidey and the general events that they experienced together.
It is possible that heroes outside earth during the events of No Way Home could remember who Peter Parker is, such as Thor, Captain Marvel, Nick Fury, and the Guardians of the Galaxy.
After a few emotional goodbyes, Doctor Strange performs the spell and wipes all memories of Peter Parker from the main MCU universe. Spider-Man: No Way Home's ending shows Peter starting his new life where no one knows he is, including his girlfriend, Michelle Jones-Watson, and best friend, Ned Leeds.
Tom Holland reveals he'll QUIT playing Spider-Man unless one condition is met - despite his desire to star as superhero again.
Michelle Jones-Watson, most commonly known as MJ, is a fictional character portrayed by Zendaya in the Marvel Cinematic Universe (MCU) film franchise, an original character within the media franchise that pays homage to Mary Jane "MJ" Watson, a recurring love interest of Spider-Man in comic books and various media.
We won't learn the full story behind that disaster until issue #26, but the series already seems to squash the idea that Peter and MJ will ever permanently get back together. Peter has recently started dating the Black Cat, and issue #20 makes things more official.
Happy Hogan brought Peter to the Avengers Compound at the end of Spider-Man: Homecoming, where Tony offered him membership on the team. It took Peter a moment to take it all in, but he ultimately rejected the proposal because he wanted to remain grounded and simply be a friendly neighborhood Spider-Man.
It all started when the Rogues were supposed to move back into the Tower after their pardons. Actually, it started when Peter jokingly called Tony 'dad' in front of them. After that, the Rogues assumed that he was Tony's illegitimate son. Tony—being the devil that he is—decided to go along with it.
The kid in question was none other than Harley Keener, the kid from Iron Man 3. If you pause the video at the 4:06 mark, you might be surprised to learn that this is the same kid who appeared in Iron Man 3 and assisted Tony Stark in some way.
Doctor Strange in the Multiverse of Madness indicates that Doctor Strange remembers Peter Parker in a specific way after the ending of Spider-Man: No Way Home.
From time to time, the Eye can be seen as a manifestation on Strange's forehead which gives him special powers. Doctor Strange's third eye (the Eye of Agamotto) in the comics, according to Bustle, represents wisdom of the sorcerer Agamotto and his Vishanti.
Tom Holland will be reprising his Spider-Man role within the Marvel Cinematic Universe (MCU) and Marvel Studios boss Kevin Feige says they are already working on his comeback. “All I will say is that we have the story,” Feige said in an interview with Entertainment Weekly.
He wasn't trying to show off to Peter Parker and be cavalier with his spells. He was trying to help a kid that he really fell for. A kid who lost his mentor, who lost his way, and lost his life, really,” the actor said. “He looked at this person as a fellow foot soldier rather than viewing him as a teenage kid.
Spider-Man's agility, coupled with his web-slinging abilities, makes him a formidable opponent against Scarlet Witch. His ability to move quickly and unpredictably could give him an advantage in battle, making it difficult for Scarlet Witch to hit him.