It's more so people don't care about T'Challa and care about Wakanda the concept and not the actual place or the franchise. They see it as "Black Excellence" then ironically turn it into the opposite of that with their ishtty pet OCs that cause more hard and damage to the franchise then whatever little benefit they THINK they bring...
I seriously want a MK BP title again that just tells T'Challa focused focused stories or have the actual solo focus on him and then they can shove all these OCs into Wakanda forever or whatever the he they want to call it books. They only take up panel space in the main title and take away from the character.
As for Peter, they have shown that he can support two books. They can have a Spiderman ongoing with him as a maturing adult and a second Spiderman"homecoming" or however they want to title itz where he is a young adult.