Because it will end up on the decentralized YT and no one can take it down. The videos will always be there, forever. Yeah you can find that stuff on the regular internet now, but it can be taken down. You can eliminate each source of that kind of content, or avoid it. People looking up nefarious videos do so on different websites than people trying to listen to new music or watch PewDiePie. If people can just upload it to a YouTube-like service without any type of repercussion, that service will end up with a lot of this content, and regular users will get scared away. The shit taints the chocolate bar. That is my point.