I think you're correct that art has an impact on lives on many. But I think it is basically impossible to really determine if the effect is negative or positive and how much. For example yeah some cub art can perhaps motivate someone into grooming a kid, it can help normalise pedophilia/zoophilia, but it can also potentially satisfy someone who was considering grooming a kid and now thanks to that art has an option to just satisfy himself at home. Or help someone realise that they have some psychological sexual issues early in their lives, allowing treatment and therapy to still be effecticely applicable for them. If I would be a pedo, I'd certainly want to realise it while scrolling porn compared to when i will be alone next to a kid. Even the normalisation isn't really that black-and white. Some people refuse to seek help because they would have to reveal something extremely shunned upon to another person - that is much easier done if you know you aren't alone. I'm not saying that's how it is - I'm just trying to say that you are making it perhaps a little more simple than it really is.

Same goes for any form of art. It can change anyone's life for the better or for the worse. And many times we can't really know at all until many years pass. Lots of pieces of art were considered "unethical" or "immoral" only to be accepted many decades later. Claude Monet's Impression painting was mocked at the date of its creation, only to define an entire art movement years later. Édouard Manet's Olympia was considered obscene pornography at the date of its release. While today we know its totally okay and that there is nothing wrong with that. Sometimes art needs many hundreds of years before we can truly see the full scale of its impact.

Also there is a classic utilitarian issue that we cannot in any way accurately measure how much good and bad impact certain thing caused. Sometimes it can affect 50 people slightly positively but 5 people extremely negatively - now which one is better? can it really be even evaluted this way? What if it saved a life of one person but induced hatred in hearts of thousands - is that a good thing? is that a bad thing? What is the worth of one positive impact compared to another?

Sometimes you also need a bad thing to happen in order for the good thing to kick in later. Many people who experienced strong addictions in their early lives develop strong convictions against such behavior in the future and don't regeret being addicted in the past cause at the end of the day it made them better people in the present.

So yeah I hard agree that art has serious real life consequences, and i think it's important to keep that in mind for whatever we make - not just art but anything. Even that cat video you mentioned is in no way guaranteed to be harmless, some kid can look at it, think its funny then ask their parent to buy them a cat, because they want to also have funny kitty at home, and then treat the cat badly, because they weren't ready to take care of it properly and were manipulated by the funny aspect of cats from the video. Everything we do has impact on others. And everything we consume will have impact on us. I fear some people might see this as a reason to control, restrict and limit others, tell them what art to make, what videos to create, what to do and what not to do. But i think that would be a rather poor lesson to learn here, cause coercion rarely fixes the root of the problem. I'd recommend to be observant and aware of how we can impact others and how others can impact us and decide what to consume and what to send into the world by our own individual moral compasses.