Yes. My younger sister was always objectively better than I had been, and while my family was not as blatant as yours (seriously! What they do to you almost amounts to abuse if you ask me!) they subtly acted similar. Not expecting me to do well on my own, I was never fast or good enough... Yep, been there.
However! I've grown up and found my way, and my sister and I are closer than ever. She, too, hated this dynamic. And she told me that actually it was me who enabled her. You see, when I learned something new I was excited and got home and talked about. And she listened and learned. She has a better talent for math and numbers, but in the end when she learned something in school she basically already knew it because I taught her.
And I hated going to places alone, so once when I was in tenth grade I dragged my seventh grade sister to a film club for English movies. The teacher said he didn't think she can keep up but she was welcome to try - and she did. She told me years later that for her there were no limits because of age or assumed ability. I asked, she was allowed to try, and she innocently just picked things up. She said this for her drove home the point of "doesn't hurt to ask" and that this opened so many doors for her.
Objectively she is still "better" than I am. Very successful with a straight career, earns more too. But that's not important. We're still learning from each other and together, and we do our best to lift each other up. And she knows what it's like to grow up in a toxic family, so she gets me.
I guess my point is that life is not a competition. And the "problem" in your situation is not you nor your abilities. It's your parents favoritism and sabotaging and disparaging you. You are not your sister. And that's normal and great. You're different people with different strengths and different ambitions. You will find your way. No matter if it's writing or something else. Don't put that much stock in what you're parents say and demand.
A good GPA doesn't guarantee a good job or a good life. What counts is if you like your life, because you have to live through it.
Not gonna lie, you sound as if you think controlling parents are in the right, the way you say they should have access.
That's a resounding fuck no from me.
It doesn't matter if kids fuck up or not. If they do, like your son, they hopefully learn a valuable lesson that apparently they have been spared before, for whatever reason. Maybe they never really had to put effort in studying in high school before - I saw a lot of that in my friends at college, they completely underestimated that college is harder than high school.
Or maybe they never learned to get shit done without parents nagging. Especially in that case they need to learn, for you will not always be there to nag. Helicopter parenting is a sign of lacking confidence in your kid's abilities. And even if the kids are fucking up, mistakes must be made in order to learn.
It's not your life, but your kids life, and your kid needs to live it. Let them. Support them if you can and they need help, but don't enable them - if they keep fucking up, let them unfuck it themselves are the third time. Otherwise you'll do your kid a disservice and make them unable to deal with life.
And I'm not saying don't help them if they ask for help, like when they can't figure something out on their own. Help them help themselves as much as possible and try not to fix everything for them.
You controlling the grades is trying to fix it for your son. How will he ever get work done later on his own? Many neurodivergent people don't do well in-office or in a job setting in general. In a home office setting or if you are your own boss the skill to self-motivate is even more important.