this is a an online community.  not an art class site, or a training site.  it's not even a store with a community, because the community pre-dates the store. a  tons of people post just to put up something they like and to have other people they like enjoy it.  asking people who post like this to share constructive criticism is like asking people who invite each other to dinner parties to share constructive criticism about cooking.   you can complain that everyone is just exchanging pleasantries instead of analyzing the ingredients of the appetizers, but that's not really going to do anything but create discomfort all around.

lots of those popular artists get free products because they put out work quickly, consistently and have a large audience.  so even if they're not selling their work, they're part of commerce.  and business isn't about being the best, it's about being popular. how you get to be popular is just the means by which you've succeeded in business.

i recently looked at the highest ranked, and i saw some work i didn't think was as good as some of mine, let alone that of the people i follow (most of whom are better than i am).  i also saw some images that were absolutely great, truly professional works.  sure, there were people on that list who are just part of the group of people who keep commenting and ranking each others' works.  but all that meant to me was that i couldn't use the list as a filter to find new and interesting works (and artists), and that even if i ever get back to posting, not to hope to be popular.  ever.  because i doubt i'll ever be great, and i know i'll never be an online Heather.

if you want constructive criticism a) ask for it each time you post, and b) actually try to use it.

i participated in the "critique group" here, and then the critique forum before it died.  i spent a lot of time on critiques of artwork by people who said that they wanted to get better.  a lot of time thinking about how they could improve their work in terms of what they seemed to be trying to accomplish and what was already good.  it was a pretty large group, but only a few of those people used any criticism at all.  most of them just kept doing the same thing they always did, with no changes to lighting, composition, materials, or any techniques.  no experiments, no discussion of trying to improve, just the same stuff, and the same explanations.

and that's cool.   i still follow a lot of those people, because they're great artists.  some i haven't commented on like i used to because i got incredibly busy.    i'll probably comment more soon.  some i (very frankly) won't bother with because even though they asked for critique all they actually want is affirmation.  for me, if the work stays the same, even if i like it, i'll only repeat myself if i feel like it's important to keep someone going as an artist, or i just like the work that much.

it's also cool that some people said they wanted critiques, but then complained when they actually got them.  i find that this whole thing is kind of like a bunch of people talking about working out.  even with the best of intentions, there's going to be a lot of people who find the actual practice too difficult and uncomfortable.  if you're asking for critique, it means you shouldn't be working comfortably.  you should be pushing yourself beyond that, to do something difficult.  it doesn't matter how you (try to) advance (artistically, technically, conceptually, emotionally, etc.), as long as you take a step in some direction rather than standing in place.

if you're not going to push yourself and take advice (sometimes, you just need to grow in your own direction), don't ask for critiques.  because when you really do need them, people probably aren't going to respond.

frankly, for me, technical information is either educational or just noise.   99.9% of the time, the main problems i see aren't technical problems, they're artistic ones.  for instance, VSS, IDL and Poser 8 aren't going to help your realism if you follow the current trend and place a front lit figure in front of a gorgeously lit sky (sunset, full moon, etc.).  conversely, there's a lot of tropes in western art that have everything to do with norms and nothing to do with realism.

but, in the end, the best way to get good critiques is to give them.  back when i was active in the galleries, a few people who posted "wonderfull!!!"and "fabulous!!!" to other people's work would write, "love it, but i wish...." on my work because i was giving pretty thorough critiques (max of  2 hours writing one- yeah, i'm slow).  

let me warn, it actually began to hamper my work.  because i would start editing myself immediately upon starting.  knowing you'll have to read a page or two of critiques after you post can be daunting, as can incorporating past critiques.  the downside to self-publishing is losing creative space to the viewers.  artists used to have lots of time alone and undisturbed (well, those without children).  now we're constantly connected to our audience.  can you imagine what the Mona Lisa would look like the general populace had been able to critique it immediately and freely? Van Gogh was unpopular in his time, but can you imagine if he'd been posting here and asking for critiques?  we'd either have less of his works, or some boring, mainstream ones.

so find a balance that suits you, and be happy as others find theirs.