Speaking for myself, it's true that writing can get stressful, especially when I get writers block, but the difference is that I could have written all my fics until now, and keep them in my Google drive. But I chose to post them on Ao3, instead.
"Oh, but SC can't take criticism."
"Readers also have an opinion."
Wrong. I can take criticism as long as it's constructive and don't mind readers saying what they think as long as they do it in a respectful way.
As a reader, don't come tell me what I should have done or that a certain character wouldn't "say that" or act a certain way, because if I wrote him/her to say and/or act that certain way in my fic, it's because he/she does.
There was a reader who once commented that (AO3) was a public website and that people could get curious and comment, which is partially true.
People can indeed ask questions, but when it comes to the Privacy category, AO3 has this following options:
Which means that, in the end, and to put it in simple terms: a reader only comments if, when and how the writer allows him/her to do so.
And of course there's also the block button (that I won't hesitate to use) in case the reader truly crosses a fucking line.
I'm a reader too, and although I'm not one to comment on other writer's works often, I know that all of what I'm saying in this post, applies to me as well.
Respecting people and their works, is one of the easiest things you can do.
If something in that fic is not your cup of tea, drop it. Leave quietly.
Because otherwise you'll be disrespecting and harassing real people over fictional characters.