The MCU works because it's 4 or 5 individual, complete franchises coming together to create a mega-franchise. Thor, Captain America, The Hulk, and Iron Man all have their own supporting casts and rogues galleries. Venom, Black Cat, Scarlet Spider, Puma and The Prowler do not.
This is a terrible idea. Make 6 Spider-Man movies if you need them to tell the story you want, but don't try to sell me a Scarlet Spider film.