It's a very subjective subject.

You can create art with Poser, but very few do.
Is it CG? No.
But at the same time, I have seen Maya student showreels... which had Victoria in them.
Turbosquid thrives on the high end content and people obviously buy it, so not everyone models everything from scratch.
Comparing Poser with Avatar is silly. That's a whole other level and should get you laughed at.
However...
Avatar was not made by a single person, who modeled the figure, textured it, animated it, lit it and integrated it.
No. That was done by a team of people, with specialized modellers, texturers, animators and so forth.
So most CG people can't point to Avatar and say "I do stuff like that" either.
I've seen superb 3D Art done in Poser.
I've seen superb 3D Art done in all manner of high end programs.
I've also seen the crap people produce, no matter what application they use.
Just because someone uses a high end application with several 0's behind the first number, doesn't mean they automatically produce top notch stuff.
And just because someone uses a low end app doesn't mean they can't produce high end imagery.

Whenever someone says "Poser is crap, you should use 3D Max" or some such thing, I always say "It doesn't matter what tool you use, if the USER'S ABILITY isn't top notch, then you get crap. Regardless."
So don't question what application someone uses. Question their level of skill - and don't judge the skill by the tool. If I hand Poser to someone who only knows Max, they will produce crap -- until they know how to use Poser to it's fullest capability. It's that simple.

I actually found that people who do CG professionally, and who know their stuff, aren't as quick to jump on the "It's all crap" bandwagon. The naysayers are usually hobbyists. The professionals know about time constraints and learning curves and what tools, hardware and setups you need to do a proper job.
Most of us can't afford that, and they are well aware of it.
I've never had someone look down on me for making an honest effort and trying to do the best job I can, with what I have. Instead I got tips on how to improve something, occasionally some headscratching when I say "It can't do that" and other solutions were offered instead (or a downright "Heck, I don't know how you did that, but if it works...")

There will always be naysayers.
I'm ignoring them. :)

Silke