I think critiquing is healthy and fosters learning and improvement, however, some folks do not like to be criticized unless the criticism is accompanied by accolades and compliments. I therefore never offer critiques, especially online, unless I am asked.
More problems- some folks do not know how to offer a constructive critique and perhaps an underlying well-meaning criticism turns into an unpleasant exchange. Some folks just enjoy mean-spirited rants that are far from constructive.
Other folks don't know how to accept or process a critique and the battle ensues. Oftentimes they ask for a critique and then resent the responses. My advice in these cases is "If you can't take a punch, don't enter the ring"! Also, there's no reason to "punch" anyone. I am asked to critique an image I feel is a total 'DUMPSTER FIRE", I simply decline and say I do not understand the image and am not qualified to judge it. Who knows?- to someone else it may be a masterpiece!
The ironic aspect of this and many other forums is the admins and some of the "moderators" or "self-appointed police" will complain about a misplaced or miscategorized post or image and yet allow and sometimes participate in all kinds of protracted infighting- weird!
My advice- If you ask for a critique, just take it for waht it is worth and consider who/where it comes from. Whether you like or not, thank the critic and move on. If you receive an unsolicited critique- do the same and move on. Do not feed the trolls- they flourish on pushback and arguments.
Online forumes are just like everywhere else- PEOPLE. You have the good, the bad, and the ugly. Enjoy the good and ignore the bad!
By the way- being a professional photographer isn't all fun and glamour. I am surrounded by and inundated by critics- clients, co-workers, staff, art directors, ad agency account executives, my lovely wife, kids, and grandkids, and I can swear that even our cat gives me a "dirty look" when he disagrees with his menu. As Roney used to say "I get no respect"!
My response to a scathing and nasty criticism is "Thank you, I'll make a note"!