[pzo]

for 4chan maybe that's true but I'm not sure what about some public whatsapp group? I have been part of few public hiking/travelling group and even though I have most of them muted (to avoid distraction) all pictures end up in my Photos 'Recent' Album.

[benzoate]

If you see something, say something, and report the person sending that stuff.

[cruano]

You can turn that off in Settings -> Chats -> Save to Camera Roll

[replwoacause]

But what if you don’t realize you can do this or you forget to? This should be off by default if you ask me.