So, if someone secretly photographs you masturbating and posts it online, you're fine with that?
That seems like a non-sequitur, and I'm sure there's a tort in there somewhere, or a copyright claim, but I wouldn't care about being "objectified" or any such nonsense, and if it caused me no actual harm I wouldn't really care.
But someone else may need protection from your mean tweets, and those of others. Cyberbullying has driven many people to suicide.
Children might indeed need such protection. Children have indeed been driven to suicide by cyberbullying. Children need protection from many things adults don't.
The internet is one of the most potent kinds of 'firepower' we have ever seen. It can let someone inflict asymmetric and widespread harm to another's reputation from a device they can hold in their hand.
I think slander and libel laws are good things, but there's a difference between causing someone monetary damage and hurting someone's feelings. When an SJW hate mob costs someone their job, that's real, monetary harm. When someone makes an off-color joke, get over it.
It can be used to inspire people to commit terrible acts.
This is starting to look like a free speech discussion. Look: slander, libel, calling for immediate violence against a specific targets, yeah, fine, that's illegal because of real harm. But speech that hurts someone's feelings? Own your feelings - realize it's your problem if you're offended.