Curate, connect, and discover
By the way, fanfiction isn't the place for reviews or criticism.
When you're a published author, it's like you're preparing a meal in a food competition. You expect a rating and to be told what worked and what didn't to improve your craft and embark on your career.
When you're a fanfiction author, it's like taking some of your free time to enjoy the process of baking cookies and then offering them to someone to be kind.
If you take a cookie from the plate, you don't spit it out and tell them it sucked.
Unless the writer asks for your opinion, you can keep it to yourself.
Adding this to clarify, and you don't have to agree with this by any means, I cannot force you to, but the reason Ao3 and Fanfiction isn't the space for criticism and ratings...is that it is a fan space created by fans for fans.
It isn't school.
It is a space where people with the same interests can congregate and enjoy the same fandom.
When you think about commenting on an fanfic authors fics, don't think if it as fishing around in your pocket to give them a compliment.
Compliments are nice. Most everyone likes compliments.
"I like your character development."
"You paint wonderful imagry."
Those are comments that are compliments. Speaking for myself as a fanfic writer they're nice, but they're not what my fan heart craves.
I want engagement with my readers.
The best comments I get aren't talking about my skill as a writer, but what just happened in the story because you and I (the reader) are already fans of the world created.
Comments like:
"NOOOOOOOO!"
"Did she actually just do that?"
"EXCUSE me?!?!"
None of these comments are compliments and none are critical. They are emotionally aligned with the story. They are engaged and with this engagement we create a little community in this tiny little space we get to call ours.
I cannot stop people from saying cruel things, but I can inform those people of the "dangers" so to speak when people treat fandom spaces like Ao3 as if it's Goodreads.
Writers, who write for themselves and offer it to you out of kindness, can decide that if people are just going to spit out their cookies they don't need to post about them anymore and that is how fandom spaces die.
If you don't like the flavor of cookie they made, or you're allergic to one of its ingredients...don't eat the cookie. Put it back for someone else to enjoy and then go find the flavor you do like.