Yes, if you look hard enough, you can find anything. But I think the idea is to make it so that the bad things don't just continue to float around where people not looking for it might see it.
Just like terrorist content (how to make bombs/attack infidels and such) still exists, and those looking for it would probably find it, but the governments are trying to make it so that innocent people that have no inclination to perform horrible acts don't run into it by "chance". And just like they did to Muslim extremists and violent ideas in that front, they are now trying to do in other areas.
I've been on the Internet my entire life and not even once I've seen something I didn't want or expect to see. It's simply not possible to force people to watch a several minutes long video or read a manifesto with dozens of pages, so I don't understand this sentiment.
Just like terrorist content (how to make bombs/attack infidels and such) still exists, and those looking for it would probably find it, but the governments are trying to make it so that innocent people that have no inclination to perform horrible acts don't run into it by "chance". And just like they did to Muslim extremists and violent ideas in that front, they are now trying to do in other areas.