Facebook reports ~20 million instances of child sexual abuse materials a year. My understanding is that this material is largely transmitted by message (i.e. people aren't posting it on their wall, but sharing it in chat). Regardless of your ideological convictions, the fact remains that one trade off of end to end encryption is a reduction in ability to detect, track, and report CSAM.

My intuition is that our current trajectory will lead us to a "worst of all worlds" case where governments continue to spy on and suppress people by subverting end to end encryption at some level, but pedophiles will trade their material with impunity. Ideally, I would like to find the opposite compromise, where we could detect and catch criminals while maintaining privacy. This has been attempted by law, due process, warrants, and such - but that attempt is subverted by the government not following the law.