Well, I don't know about that. I'm a Poser artist too, I mean, I don't ONLY use Poser but  I make Poser content sometimes and have to do renders in it for my products. I've no problem with critique. I've also run into a few Poser only artists who are of a similar mind. 

I think the thing is, alot of people who critique don't actually critique at all, they just go in and say, "This sucks" or "Lighting's off" or some other vague thing like that. A critique should:

1.  Commend the artist on the merit of the work
2.  Point out specific errors within the work

3. Suggest possible ways of improvement

Most people will do #1 or #2 and leave it at that. It is rare, I mean RARE that I see folks doing all three. I think if more people were to do all three, there would be less of the type of attitude you mention and also less cause for it.