How long could readers manage?
Problem with the abuse, any kind of abuse be it parental or sexual or bullying, it all takes place over the long periods of time. It is not a one-time thing. Time is the essence, not the graphical intensity of it. There has been a lot of extreme stuff written. Web novels readers aren't much interested in the long-term problems, any kind of long-term problem, they demand resolution, and they demand it fast, because that's the nature of the web novel. There is no initial investment, and the alternative is only one click away. This is something which doesn't happen with traditional publishing where there is, in fact, initial investment, be it in effort (bringing the book home from library, then returning it) or monetary (paying for the book). In web novels there is no such thing. Readers could leave with the click, and will leave with that click.
Did you notice how fast could the web novel's protagonist solve problems, I mean, on average?
It's unusually overnight (or at least since the next chapter)
And that's the problem.
You couldn't portray the gruelling, long term, nature of the abuse.
Your audience could sometimes have a stomach for cruelty, but always, always lack patience.
Go for your abuse routine for longer than three chapters with no resolution in sight - let it be running away or good old patricide - the readers will leave. Hell, they might even leave after one chapter, and will most likely leave you a bad rating to remember them by. Then, the story would be dead, and the message you want to send lost. There is no story is no one shows to read it, or is there? It's up to you, really.
And then there is an elephant in the room. It's pink, and it's called escapism. Do the readers even want to read about the very real issues of the real world, they read to escape them, and when you think of it, what is the most likely trauma in young adults that makes a predominant part of your reader base? If any, it would be abuse, and you don't want to poke that.
