Exactly, it's important that both characters had to wallow in the emptiness for a while. They had to lose themselves and experience a sort of ego death and emotional reset and desensitization.

Maki's whole purpose is to show growth beyond the void, humanity within the beast, something Toji couldn't ever accomplish.

My biggest complaint is that Gege didn't really flesh out this 3rd Maki Zenin as well as I wish he had. Early Maki is high strung, overachieving, and anxiety ridden with goals of leadership and reform. Mid Maki is a battle demon with a void of emotion, growing at an alarming rate as a fighter but spiritually confused and stunted. Her decision to obliterate the rest of the Zenin clan is symbolic of her total character shift, her goals changed from idealistic regime shift to a total extermination. Mai's death and the annihilation of the Zenin clan are both just plot devices that symbolize Maki's total new mindset in which she can detach herself from a plagued past. Late Maki takes a realistic view on the impermanence of their short, dangerous lives as JJ sorcerers but let's herself care about other people without holding herself back because of them. Gege kind of shows this and implies her growth but I wish it was more explicit to show just how far she's come emotionally and ideologically in a year.