Interesting theory, but no.
1. We've had "Edgier" stuff than this in kid's shows before. We've had "Edgier" stuff than this in MLP before.
2. Even if Glimmer was abused or neglected by her parents, that doesn't justify the shit she's done.
3. ATLA, dude. Zuko's dad scarred his face for speaking out of turn. Aang's whole race except him got wiped out, and they walked through the skeleton-filled ash-covered remains of the old air temple.
4. Glimmer being a shit person with a shit backstory and shit personality isn't what makes me hate her. It's partly that she's constantly forgiven for being a shit character despite never making an effort to become a better person, but it's mostly because the writers keep shilling her or her and OCs connected to her whenever she shows up. The writers consider this piece of shit the bee's knees, and they think if they shove her down our throats enough, we'll eat her up just like the glimmerniggers do. That's what bothers me. The show expects me to love this piece of shit, other pieces of shit expect me to love this piece of shit, and they all get buttblasted when I don't. The show calls me Quibble Pants and the Glimmerniggers call me "Nigel", that faggot that hates all of MLP equally for being a popular children's show on around the same time as barney, and both are too retarded, distorted, and deluded to get their straw replicas of me even remotely right.
Still, this is the first legitimate piece of Glimmer discussion not consumed by "Haha this shitpost horse makes you mad and I'm ironically posting her to bully you off the site and make you butthurt!" Glimmerniggery in quite some time.