There are spaces where the comments are in other spaces after the fact, though; for example, in places like ff.net, you're more likely to read comments after reading the fic. In AO3, Livejournal and Deviantart and a substantial amount of platforms, these comment sections are placed below the work. These fandom spaces are the origins of the phrase, and in it it's not rare to see comments that are reactive and directed straight at the creator, not other readers. At best, what you get is you get an affirmation to what you thought, and usually not the first thing you read. The most commonly used sorting for quality for many people is ratings/kudos/favorites. There CAN be different dynamics at work in places where there is a review section prior to entering a work, like SH or NU, but in general that is not how a lot of sites are laid out. I agree with you that such a function of reviews exist and is valuable, but it's also not the primary use of it in online spaces that use "don't like don't read".
It doesn't matter where the phrase came from, only how it is used.
Whether you can see some comments directed to the author or not (a lot of that might also be because the author directly confront the writer of the criticism), this doesn't change the fact that most aren't directed to the author. Most are just readers talking to other reader. It has no bearing on what I said.
And how the sites is used isn't dictated by what you think or feel it should be used. Heck, it is not even dictated by the site creators. Sure, they can impose what they want like how Tumblr doesn't want they platform be used for pornography (the adult content ban) but you know what happens.
I do write a lot of NU (and general book) reviews myself, so I do like using this version of the reviews. I think this viewing works for books, movies, and "better gated" media. But online spaces where you are dropping something deeply personal into the uncaring abyss is not the same as publishing a book and reading Amazon reviews of it. Both the personal and the professional can end up coexisting in the same space, and despite all signposts and explicit warnings, some people do not care to delineate them.
They might have differences, but so what? Why should they care?
I'm not being callous, I'm being realistic. I think you even an idea about this. As you said "you are dropping something deeply personal into the uncaring abyss". It's uncaring, Seriously, why are you expecting them to care?
The thing is you can't control people. You can't impose your will on them. Once you put something online for everyone to see, it is now out of your control. Write something very racist in twitter? Post your naked photos on Facebook? Write a fan fic about something (like shipping) that has lots of haters? Good Luck!
As I said, I'm not being callous here. I'm just talking about the reality of the situation. It is futile to impose your will on the internet.
"Don't like don't read" specifically is heavily laden with history of people bashing works for "wrong ships", "wrong position", "yaoi is gross", etc. that it's not fair to remove that history from discussion of the term. It was intended to warn against people who come into a work with ships, sexualities and themes/subjects often presented in the summary, intending to dislike it. It is fair to complain, I feel, if a work is poorly tagged or it came up on you suddenly-- such is the purpose of the review you mention. But it is also not the only type of review levied against small-time, often hobbyist creators.
Okay. We are thing going farther and farther from the topic.
Sure, this thread starts about the phrase, but our discussion is the purpose of reviews and criticism. You essentially asserted that people shouldn't criticize a work that the author has no intention of improving, and essentially indicating that reviews and criticism are only for the sake of improving someones work. This is specially apparent with your given example of your OC drawing. No "wrong ships" or "yaoi is gross" or anything. Just a person giving criticism.
My earlier take covered only one facet, and I really appreciate you bringing up the other side. I think this is also further food for thought, for me.
Yeah. Most criticisms/reviews are just people just saying what they think. They just want to talk.
In your example, when you said that your drawing is trashy; you essentially are leading the discussion. You talk about how trashy your artwork is, so they talked about how trashy your artwork is (well, that is what I think happened). If you have talked about your OC instead of your artwork, then they would have talked about your OC and not the artwork.