my two cents....

we're conflating two different things:  is this art (which the OP didn't ask) and is it our own creation?

is it art?  sure, it's art.  art is everything from kindergarteners' fingerpaintings to adolescent boys copying manga babes to painters using oils to capture the pose of a model to sculptors creating abstract metal structures.  it's just not necessarily very original, effective, or quality art.  as hobbyists, we don't need to make great works, or even good ones.  if it makes someone happy to churn out studio shots of the most popular content, then that's great.  happiness can be hard to find, and if someone can achieve it by clicking a few buttons, that's just wonderful.

sure you can assemble things in a way that takes artistry and skill, but it's a lot harder to put originality into something assembled.  most people who use prebuilt content don't want to take that time.  using the photographer as an example, i can take 5 minutes to make a sketch totally identifiable as my work (to anyone familiar with my drawings), and i haven't had a formal class in years.  most people could, even if they had almost no drawing skill, because they'd all be uniquely off.  but it takes a serious amount of training and a huge amount of innate talent to start making photos that are professional, let alone individual and unique.

it's much harder to be original with Poser than it is either painting something from scratch in Photoshop (or Painter, or Paint Shop Pro, or GIMP, etc.) or building it from scratch in a 3d app.  even when we want to be original, we're affected by how the product we're using was promoted, and how others are using it.  and all of CG is affected by market forces and genre tropes.

originality plays into how much something is your creation.  is what you added the point of the final result?  or is the point of the final result how hot the V4 character you just purchased is?  if it's mostly the latter, then it's less your work than the creator of the character. 

sure a photographer is the only one to consider when there's no or little art involved in the creation of the subjects.  that is, intentional design (not nature shots).   but when the photo is of a model where a make-up and hair stylist spent 3 hours, a clothing designer spent months, and the model herself is using her own art to make the photos look great, then it's not just the photographer's work.  it's a collaboration.  saying it's one person's creation would be like saying movies only belong to the director.  conversely, it doesn't take anything away from the director to say that everyone from the best boy to the director of photography contributed to the movie.

so, personally, i'd say most Poser work isn't a single person's creation, in general.  it's a collaborative effort.  and how much is the artist who hits render and how much is others depends very much on what that artist wants to put into their work.  and i think there's enough room on this site for the people who just want enough of themselves to say "hi! here's what i think is hot!" and those who want to direct epic narratives like JOELGLAINE.  there's no need for the former to justify their work as "high" art, and no need for the latter to simplify their work to make it more popular.  the lovely thing about this site is that we don't even have to follow our own requirements if we don't want to that day.  we can create what we feel like creating and enjoy it for what it is, not compare it to what it isn't.

that said, we're still all hobbiests.  so i don't think it's realistic to expect everyone to have comprehensive credits everywhere all the time.   but it's nice to think that we're all grateful for what the community has given us, and that we all try to do our bit to give back.  even if it's only in small ways.