What is the point of designing technology for people to use that does not account for common "people problem"s?
I think it's important for people to understand just how large of an issue CSAM is on the internet. This recent article has some numbers: https://www.comparitech.com/blog/vpn-privacy/child-abuse-online-statistics/
Basically every platform that allows users to upload arbitrary content has this issue. It doesn't even require presumed anonymity, people share this stuff on Facebook. I think Darknet Diaries Episode 93: KIK also helps show just how prevalent it is.
You can't just handwave CSAM as a pretext. Every file-sharing platform that allows anonymity is rife with it. To operate an anonymous file sharing system is to enable child exploitation.
From left to right:
5.25 in (130mm) and 3.5 in (90mm}
https://en.wikipedia.org/wiki/Floppy_disk
VHS tape
https://en.wikipedia.org/wiki/VHS
Compact Cassette
https://en.wikipedia.org/wiki/Cassette_tape
Open-reel magnetic tape (as opposed to a cartridge or cassette)
https://en.wikipedia.org/wiki/9-track_tape
https://en.wikipedia.org/wiki/Magnetic-tape_data_storage
Punched card
https://en.wikipedia.org/wiki/Punched_card
See also:
108 Rare and Bizarre Media Types - The8BitGuy (much has been forgotten)
Bird Song