It breaks my heart when I see posts about writing criticism discourse, because its awful that there is even discourse about it. If someone asks for feed back, and you have feed back you want to give them, give it to them in a constructive and polite manner. Theres no reason to be an ass about it. And if they don't ask for it, then don't give it. If they request positivity only, and you don't have anything overly positive to say, then say nothing. Its not hard.
Personally, I like sharing my writing with friends and hearing their feedback. I took a creative writing course and part of it was peer review and teacher comments. The professor was always direct with his suggestions and some I didn't entirely agree with, such as his war against -ly words, but I did listen to and respect his comments 99% of the time. Because I knew and agreed to his constructive criticism. And it was always constructive. He never made me feel bad about my writing, and if he liked something, he said so. I signed up for his class to get this professional, published wisdom, and I got it.
But of course, I also got reviews from some classmates too. Luckily, I never got anything truly nasty, and I in fact got plenty of lovely and constructive comments, but I do remember in a scene assignment one person in particular commented a lot on my assignment. And some were good points, others were nitpicky, but one made me laugh at the utter absurdity and audacity of it. This person commented on a scene assignment of a person they never met in regards to my using the nickname 'Ria for Maria: "This is a cute idea for a nickname but I'll note that it reminds me of diarrhea. Or gonorrhea. Maybe not nice." Honestly? Made me burst out laughing at the sheer absurdity of what was written. But no. It was the following comment, left by the same person that made me go "bitch this is getting ridiculous." They wrote: "Can a voice crack with tears? :)"
Why yes. Yes it can. And that smiley face was so uncalled for. Because here's the other thing about crit: it should always be helpful and constructive to help the author improve. That was not helpful. The 'Ria comment? Arguably helpful, but the second person that commented on that same nickname that said it should be capitalized (it wasn't at the time) was far more helpful and wasn't throwing shade. But asking if a voice can crack with tears then ending it with a smiley face was not helpful. Especially since it can. Now, if it was reworded to: "I've never heae that before, can a voice crack with tears? Did you mean crack with emotion?" That would be fine. Or they just could have opened Google, found it is a thing, and said nothing.
Point is: I asked for criticism and welcomed it in this instance. It was to improve my writing. And I took to mind all constructive and polite comments I received. But the second you become condescending or rude or nasty (in general, the person in my example wasn't nasty), even if that criticism was initially improved and welcomed, its not anymore. Because it isn't helpful.
Be constructive, not critical.