Antinatalist? Children don’t sign up for anything. They’re born.

Sure. Is it ethical to force a sentience into this world (without asking it), then forcing it to live strictly by your rules for the next 18 years? To bring that sentience into a world which it will inevitably wither and die and lose everything dear to it, because it exists in a frail organic shell?

Consent is critical, and I don't think any life-event breaches consent more than existing in the first place. I do not think having children is a good thing, morally speaking. It is not possible to obtain the consent of a being before it exists - as such, the best route is to not bring said being into existence in the first place.

I don't think it's inherently virtuous to be a parent, or that your children are property that you can treat however you want.

It's a responsibility, and if you can't/won't take care of them properly then you shouldn't impose the burden on them or yourself.

By what metric did they not take care of them properly? I understand that the way they raised their children is not acceptable in your subculture but they’re not in your subculture. Is there some principle here? Getting all one’s children through college is more than a lot of people with two kids manage.