Posters of the golden age of Soviet cosmonauts

It's not. Books are written by humans. You expect them to contain fiction or opinion. Pictures are taken by mechanical equipment with no agenda. "The camera never lies" etc. Obviously you can also stage a photograph unrepresentative of reality using techniques other than Photoshop, but the general expectation is that what you see in a photograph is what you would have seen with your own eyes if you had been there at the time.

But people also blame Photoshop when the problem is endemic. Only people with certain body types are hired in Hollywood. Then they have professional makeup artists and hair stylists make them up like a plastic doll, and then the pictures are photoshopped.

I suspect a big part of the reason the criticism is rarely taken seriously is that the proposed alternative of "normal" people is so obviously the wrong one. The average American is overweight and doesn't get enough exercise. People aren't going to want to look at that or be inspired to look like that, nor should they be. But the concept that the represented ideal physical appearance should resemble real athletes rather than stick figures or couch potatoes doesn't seem to have occurred to anyone.

Both the US and former Soviet Union are culturally backwards in many ways, but each has aspects worth learning from. One can easily think of societies improved beyond both "theirs & ours," which also unleash imagination.