I remember being in IRC chatrooms and having predators galore trying to get me to hang out with them. From my understanding, the problem hasn't gotten any better.
A parent would be smart to limit some internet access to their children. We ID at bars and brothels (where legal), the way I see it, the day my son is willing to learn to jump through hoops to access pornography is the day he is ready to watch pornography. I'm not all too concerned about them working around these things, but I'm concerned about easy unrestricted access.
We will likely release some of these restrictions as our trust in our child and their recognition of the problem sinks in over the next few weeks. I would never consider an outright ban or prohibition because I agree it does have some of the affects you mention. Instead, this is a resetting of expectations for our child around what level of risk is acceptable.
What does this mean? Isn't it better to teach them how to be safe so when they grow up they will be safe? Instead of teaching them nothing but to not trust you?
Once your monitoring no longer exists on their devices, what do you think they'd do?
Now imagine she is asked to meet up.
Sure, teach them. Explain your rules. Make things clear. But there are real people on the internet. Nice people and dangerous people. Just like the real world. You don't let them run around going to brothels and bars before they're adults, the same applies to the internet. Once they're adults the monitoring stops, of course, just like the real world.
This is a resetting for us and not a permanent state. Teaching often means letting someone fail, correcting that behavior, and then trying again. Teaching is never, "I say it and they do it."