One sees from time to time on the internet someone complaining that much critique comes from people who lack knowledge. Many of the people who comment on other people's pictures don't have the knowledge, the training, the skill to know a good picture from a bad one. Sometimes, when it gets personal, there is an attack on the commenter's portfolio, or lack thereof.
This all contains a planted axiom: that we take pictures for other photographers. It's not just a planted axiom, it's false. I could not care less what some bunch of half-baked gearheads think of my pictures. Fuck those guys. And here's why:
For the most part the person making these complaints also has no particular ability to recognize good pictures. In fact, what ability they may once have had, they have carefully trained out of existence. What they have is the ability to recognize pictures that meet the norms of their little social group of photographers. They recognize certain "mistakes" and call them out with stock phrases, and they declare a picture good when it lacks any of these supposed mistakes.
The poor ignorant sods who dare to comment do not know, or do not care about, these social norms, and so they cannot or will not shout out the stock phrases. They are recognizably not part of the social group, and therefore must be either forced to comply, or hounded out.
This is not to say that every random joe has anything valuable to add. People who lack this sort of "training" (ahem) are generally very generous, and like pretty much anything that's in-focus. But consider, what does that say? Think about that a little. On the other hand, it's not helpful for improvement. Random people, who are not part of some ugly little club, are a better source of critique, but I think you have to work with them a bit, and have a conversation.
This is also not to say that every picture is good, it's not. But there are more things in heaven and earth, random internet blow-hard know-it-all, than are dreamt of in your philosophy. Also, random blow-hard, because your taste has been trained to like a sort of lowest-common-denominator social norm, your taste is garbage and should be utterly ignored by anyone with any actual ambition.
Some contexts have a bigger problem with this than others, of course. Use caution, and keep your wits about you.