Exactly. If those are the qualifications for "stealing" someone's story, then every single comic character ever has "stolen" from another character. The second Peter becomes the second spider-man after the original dies or if somehow uncle ben shows up as a criminal involved in Peter becoming Spider-man then the concerns would be valid. The fact that Miles just had a movie where he literally uses the same superhero name as Peter, got his powers the same way, and is romantically linked to gwen stacy is way more than anything the MCU did.
Ned is certainly a case where they borrowed something from Miles and I get where that could somewhat anger people but borrowing from different characters for story purposes has happened quite often in the MCU. Iron Man was handed hank pym's role in creating ultron, because it made more sense from a story perspective and Ned seems to be the same case. MCU clearly wanted to differentiate from the previous iterations of the character so they adopted that element, the same way they changed Mary Jane. Including Ned as Peter's confidant in no way limits Miles' story. They have already introduced Aaron Davis in the movies and mentioned Miles, for all we know they could kill off Peter after a couple of films and replace him as miles and have Ned fill the same role for miles. And again it's great that Miles has fans and he certainly is a good character. It's great that so many people are attached to him so strongly in such a relatively short amount of time. He and Peter can absolutely co-exist like they do in the 616 now and it would even be great if the MCU would go the route that the PS4 games seem to be going with the characters existing as superheros at the same time.