Iron man was a pure origin story. Tony stark gets injured and captured and his only way out is to build a thing for his heart which he also uses to power a crude suit. He brings it home, his evil ceo builds a suit to fight him but Tony prevails.
Batman begins was the same thing although they did come back to the league of shadows in the third movie.
Ant man, thor, captain America, guardians of the galaxy were all mostly pure origin stories. Introduce the hero, they fight some inconsequential bad guy and win, maybe you meet pepper potts or alfred or bucky who become consequential later but that was the standard superhero movie formula for a long time.
Then they released the avengers and didn't just bring other heroes together, they introduced this new Bruce banner guy and suddenly he's a main character too. In Ultron they bring in wanda and turn jarvis from a voice over role into vision. These weren't minor characters, they were major additions to the team in context of a plot about the main characters from this one.
Wanda vision didn't do that. It was just standalone with some characters you recognized. Faws didn't either. Loki introduced a new guy but they're also making a second season so it may stay standalone.
Black widow wasnt just Disney plus and it introduced pugh, and she's getting a chance to expand her role maybe.
But here they're introducing a potential major bad guy, and possibly a good guy, into the mcu. In a Disney plus show. That's not how they've been doing it so far. If they roll out a new movie in the theaters with these characters, will they have to reintroduce them because the non streaming audience hasn't met them? Is this just lore for the Disney plus audience?