Starlin disliked Ms Marvel.
Oh he didn't dislike Carol. She was pretty much Mar-Vell's first supporting cast member and served as his Lois Lane for quite a few early stories, But Starlin was not asked when the decision was made to turn Carol into Ms Marvel. Ms Marvel was part of an editorial idea, anyway. It wasn't a writer's concept. Marvel editorial in the 70s realized they had no female lead books really and put a big initiative into play to introduce new or revamped female titles. Some of the titles in that push were the Cat (the woman who would become Tigra), Shanna the She-Devil, Night Nurse and Ms Marvel. So they cooked up a plot that the psyche-magnetron had given Carol not only the powers but the mind of a Kree warrior, which caused her to have blackouts where she turned into a superhero.
Starlin wasn't happy.
He refused to feature Ms marvel in anything because he thought the idea was ridiculous, which is why she was omitted from Death of Captain Marvel. Even much later, Starlin made sure to specifically kill off Binary (Carol's then-alias) off-screen in Infinity Gauntlet. He was still resentful.