I agree that most of what OP talks about can suck, but doesn't fall under 'abuse' for me, but I do think a method to report could be helpful for legitimate abuse.
If comments are to the point of threats, slurs, and campaigns of harassment, ignoring it or talking it through is no longer practical. It's one thing to ignore 'wow, this sucks. you should hire an artist or give up', another to ignore somebody sending that message every day, or sending 'hey, i know where you wife lives and I'm going to kill her'.
And for real harassment, nobody's going to listen to a 'hey, this may surprise you, but telling me people of my sexuality should be killed made me feel bad. could you not do that anymore?' because those people want to hurt you.
Also, most popular artists can take critique and handle some abuse, but they also have social media teams to protect them from the worst of it. The people who get hit the hardest are people with large following, but not actual fame (like many youtube stars), and the results or harassment can be truly traumatic, even on 'tough' people.