It could be that her motives and actions throughout the story are questionable and give us reasons not to trust her. Maybe she keeps secrets or makes choices that seem self-serving.
It could be that doing it would violate the established rules or plotlines of the manga world. Sometimes, certain actions just don't fit the context or the character developments.
Well, for one, teasing manga might hurt the feelings of those who are passionate about it. Also, it can create a negative atmosphere among the manga community. We should encourage and support rather than tease.
The main reason could be that looking for specific moments out of context might lead to a misunderstanding of the plot. Also, it takes away the fun of discovering things naturally as you progress through the manga.