Personal taste plays a big part in all of this. What is the goal of someone who posts a WIP? Are they looking for help, or do they just want validation that the work (that they know is really good) is really good. I’m a noob in this industry, and after seeing the high level of skill on this site there’s no way I would post my work here - I know it doesn’t measure up. But, that shouldn’t prevent me from asking for help. I have spent 5 hours over the last two days going through the “3D/2D Techniques > Modeling > Topology research” thread. Amazing discussions, examples, and links. Incredibly helpful, and I now hope to put it into practise.
It is also hard to judge a WIP if we don’t know what the final product is supposed to look like: where are the sketches & references? How close is it to the ultimate goal? Where is it lacking? How can someone say “the knee should look like xxxx”, or “the foot should look like xxxx”? Maybe that’s what the artist wanted, maybe not. It is also very different than saying “that knee will not animate correctly because xxxx”.
There are definite "do’s and don’t"s and “what will work and what won’t” with regard to modeling, lighting, texturing, animation, etc. If someone is posting a WIP and is having trouble or is unsure of their progress in a certain area, state it and ask for crits. That is a different issue than someone just posting their stuff to receive the "wow!"s and “amazing!”. I would love to be able to post something that will get "wow"s and "amazing"s, but I can’t (yet). When I can, I will probably know it. Then I can undermine everything I’ve said here by posting it 
Requesting “help and constructive criticism” is a very different issue than “do you like my artwork”. I don’t want to sound harsh, and am not slandering anyone, just stating what I think the issues & differences are.