But all this still means that if one looks after the technical aspects of his picture and the content is somewhat creative his picture can easily stand against any picture made in some high end professional app under the same conditions.

In an more real life production line there would be some people who do only models, other who do only textures, some technicians who know all the ins and outs of some renderer and some other folks to keep the production going. Which one of these is the artist now?
The limits of high end apps are not less annoying as the ones of Poser, but the limits are not really the reason for what Poser is looked down at. It's much more what is done with Poser.

if everybody would start to do his NVIATWAS in Max or Maya then there would be much more content for these apps and of course some people would look down upon the program and the users.
Or to take a different example: many people look down upon Windows98, XP, Vista because of all the users that have no clue how to use their OS and because of all the crappy actions they do. Stuff like getting viruses on their systems, slow their machines down because they install whatever stupid combination of drivers and programs, being unable to read the manuals and help themselves and so on...
How many people look down upon Win 2003 and the like? Much less. But there are much less stupid admin actions and the users usually can't do much harm except the admins let them.
Stupid actions are comparable to crappy/mediocre pictures which are the result of lacking knowledge about the used software.
Creating a 3D model after some real world object, a vehicle, building, whatever, is more technical drawing / engineering than artistic expression. Ergo, the technical drawing that many do in high end apps is on an artistical level comparable to placing models done by others in a scene and set up lighting, textures, bla bla.
While some play with figures and textures, others play with vertexes, nurbs and program/renderengine settings.

I play in a sandpit surrounded by a forest and a rivulet while you have to play in sandbox on an playground... I can with my friends dig and drag around the sand for years in that large sandpit and we have so much more freedom. Yeah, we are totally 1337! - In our sandpit...