I don't know about you guys, but if you have a younger sibling, they've probably pissed you off at some point.
In response to this, your parents have probably said: "it's just their job to annoy you, they love you, blah"

It's their job
No it isn't

It's not somebody's job to piss you off, to hurt you, to constantly be in your business.

My sister insults my weight/looks: "It's her job"
My sister gets annoyed at nothing and yells at me: "It's her job"
My sister throws a cat at me and it cuts me: "It's her job"
My sister steals (money and other private stuff) from my room: "It's her job"
My sister cuts my wrist with her fingernails because I sat down on the other side of the room and 'took her seat': "It's her job"
My sister tries to push me on the stairs from behind: "It's her job"
My sister shoves me into a fake metal fireplace plugged into the wall and I fall on it and hit my hip on the tile floor: "It's her job"
My sister kicks me in the face and makes me cut my lip and nearly have a panic attack because I think it's my tooth that's bleeding for the next half hour: "It's her job"
My sister bursts into my room while I'm talking to my friend about something really sensitive for them without knocking and yelling at me for no reason: "It's her job"

This has all happened at least once and I've told my parents(specifically my dad) about all of it and the response was "It's her job to annoy you, she loves you."

She's actually put me in fucking danger and I've told people and the only response I get is "it's her job" from my parents and "oh that sucks" from my friends. I have scars from cuts she's given me, I had a huge bruise on my hip for two weeks from the fireplace thing, and I'm pretty sure nobody would care at this point if she actually seriously hurt me because it's a miracle I've never broken anything or gotten a concussion from her so far.

This has been going on for literal years; when I was in eighth grade(she was 11) she fucking bit me because I ate the last nut bar without asking her.

I have friends with siblings around her age too, and they don't do anything close to this as far as I know.

It's not her fucking job.