Even if invasion of the privacy and autonomy of your child was the only way to guarantee protection for them from online predators, it would still not be an acceptable thing to do, in the same way the United States' surveillance state is not acceptable even if it is the only way to protect us from terrorists.
The horrors of the misuse of these systems, and the fact that they are much more likely to be misused then used for a good purpose, and will be misused far more often than they actually prevent something bad, and the fact that there existence will incentivize their own misuse, means that they are simply not worth it.
The insane obsessive paranoid controllingness that invasive parental controls enable in parents, the way it enables parents to cut children off from needed support networks and friends, further indoctrinate, manipulate, and gaslight them by censuring what they can know, and prevent them from having the privacy and space to discover and experiment with things about themselves and their identity; the constant stress and fear that it makes children undergo, because they WILL still engage in behaviors the parents want to block out because those behaviors are necessary and natural, they'll just before to do them under an overwhelming pall of fear — none of this is worth it.
We should not grant the evil, manipulative, abusive, controlling parents the tools to do this just because there are some parents who may not misuse these tools, just like we should not give politicians certain tools even if some politicians might not misuse them in your happy-go-lucky fantasy of there being such a thing as trustworthy authority.