Not accidental. Planned.
Stan Lee once said about Scarlet Witch and her twin Quicksilver, “I remember that I liked (Quicksilver and the Scarlet Witch) very much and I thought it would be fun to have villains who aren’t really bad deep down,” Lee told Comics Creators On X-Men. “We already had a reluctant hero with Spider-Man so I thought it would be fun to create a pair of reluctant villains.”
“I had big plans for Quicksilver and the Scarlet Witch. I wanted them to eventually give up being villains and become heroes. That’s why I used them in Avengers after I left X-Men.”
https://screenrant.com/marvel-best-scarlet-witch-facts/
Yeah and Mephisto, Nightmare, Mags, Xavier, etc. Were all gonna be in her show. Mutants will get their time and it should be in the next five years. They'll get all their lore and hopefully it's great. But it doesn't need to include Wanda. They don't need her. And now with her level of popularity, she doesn't need them.