I have never come across child porn in a decade of net use
I thought filtering out CP was just part of the proposed design ... ie, you've forgetting "unwanted" material.
There isn't one of us here who has never come across "unwanted material" in a decade of net use.
Obviously, what I deem to be "unwanted material" is going to differ somewhat to your idea.
So. May the majority/consensus win out on that one ...
regarDS