"We make a living by what we get, we make a life by what we give."
Sir Winston Churchill

You can think what you want, believe in what seems best for you, but one thing cannot be denied: there are some universal rules like gravity around us that apply to all and every individual. We can learn how to cheat on these rules, like closing the eyes in hope that they might not see us, but sooner or later they will get us.
There is a reason why there is lie in believe, in in pain and if in life.

When it comes to these rules you either have an ethical understanding for them, such as knowing that breathing fresh air is good for you. Is this understanding inherent, you no longer believe, hope or guess, you simply know.
Its the same with giving and receiving constructive critique as an artist. Its absolutely important and helpful for those getting the enlightenment through another individual who takes their time to point out flaws or weakness of another artists work.

Lets talk about some online-community habits...
It does cost time,yes - it even forces you to outline your thoughts well and it needs a writing that does not hurt the artist in question.
But the most important aspect of giving helpful and constructive critique is that it does help the critic far more than the one who is being criticized.

In fact: if appreciated from both sides, the act even creates a true connection between those two parties.

Sounds weird, doesn´t it? But the reason why its true is simple. It just is a basic rule that applies here: you need to be objective to realize whats wrong to point out any flaws, which in turn helps you to avoid this error yourself. (Assumed its a constructive critique)  Do this often and you are (theroretically) a master.

How to deal with inappropriate criticism is material for another post, but being objective is the key here, regardless on which side you are. If you or your work is put into critique, it means you´ve done something right, I´m quoting Bruce Lee here; you only attack someone who is in possession of the ball.

This means on the other side you need to be interesting enough to get even criticized.
No one would want to put 5 minutes writing on a piece of art that is done or looks like its done in 2 minutes. Hard but true.

Another quote about that topic is from Randy Pausch: When you see yourself doing something badly and nobody’s bothering to tell you anymore, that’s a very bad place to be. Your critics are your ones telling you they still love you and care.

In terms of social media and the possibilities we have today with the internet, it means that its far more important to make real connections to true people. That is the key to find people who care for you and who wholeheartedly support you in whatever you do. But this should always be a 2 way street. Without these "true" friends, you will get nowhere, not 10k myspace friends nor 100k twitter followers stand behind you if you fail, because the habit of accepting the - oh so easy to fawn on getting praise, will evoke exactly that you´ll fail...sooner or later.

Which lead to another conclusion, that its always easier to believe the praise than the bad words.
The best attitude you can develop is to see the "words of praise" as motivation factor that is reason to get your butt up in the morning and the critics are the ones that give you reason to work harder on yourself - to get you even later to bed.

As a subsequent conclusion it can be said that the level of critique you´ll receive is always dependent on what you give and how much popularity you gain. Sometimes not a really justified or pleasing system, but in that aspect not much of a difference to the real world.

After all you´ll always have to do with people not just numbers, screen-names or machines, and people live by rules, right?