Her Dad has as much power as she allows him to have, which in this case is a lot, and the fact is that people like Maya exist the world over, people whose lives have been so controlled and ruled their parent(s) that even when they're well into their adult years of 30s and even 40s, they still feel like their lives are ruled by what their parents think and want. Some parents have that power to make their kids feel weak, powerless, and judged and it's not an easy thing to overcome by just saying, "grow up and act like an adult", because it's serious psychological abuse.
This is where a confrontation with Maya's Dad could be a good thing, because she will likely crumble under the weight of her Dad's abuse, and so to have the MC step in and argue for her, to fight for her, can show her that she doesn't have to take it, that she doesn't have to bend to his will. In a way, it reminds of part of a quote from Batman Begins, "People need dramatic examples to shake them out of apathy". The MC doing this for her could shake her out of her apathy so that when the Dad tries to exert more pressure, she flat-out refuses and this would be of great benefit to her personal growth.