i haven't seen it happen, but i agree with you, deirde. it would be wrong to take someone's work, slightly change it, and then repost it as your own, or to make a blueprint of someone else's work in a multiplayer game and then claim it as your own to share it online.
i think avanar and forscherdrang are missing the point about reposting. the point of sharing blueprints on here is indeed to be able to incorporate them into your own work, but that doesn't include sharing it again as your own blueprint, or taking credit by posting pictures of others' work without mentioning them at all. when i download blueprints from here, i use them to decorate my own, private world. that is how they bring me joy and i don't need to steal credit by posting pictures of them. if i incorporate them into my own work that i would like to share, i would give the artists their due credit in the description or comments of the post, because that is the minimum amount of respect they deserve for sharing their hard work with me in the first place.
the disregard for artists' efforts and treating anything posted online as public property disgusts me, and as a professional artist, who tries to pay bills with my work, it makes me want to stop sharing anything i make online altogether (tho of course i'm not selling stuff i make in rising world, the feeling of betrayal and disgust is nevertheless the same. i may not be asking for payment, but i still expect basic respect). allowing people to view your work is not the same thing as giving them permission to take it and showcase it in their own gallery without credit as if they owned it, and just because someone shared a blueprint for others to use does not mean it's okay to erase their name off of it and write your own on top.
every creator may feel differently about it, but at the end of the day, the one fact that should never be ignored is that the creator's feelings are the ones that matter when it comes what people can do with their creations. if an artist says people can do whatever they want with their work, then that's true for their work, but ONLY their work. if another artist says they don't want people reposting their work, then nobody should repost that particular artist's work. and since it isn't always clear what an artist's stance is, it's common sense/decency to assume the strictest policy. people these days don't treat artists with any respect because it's too easy to rip their work from the internet and do whatever you want without getting caught. but morality isn't just about avoiding legal repercussions. it's about being kind and considerate to others.
permission to view =/= permission to use =/= permission to claim as your own by not providing credit when you share it
art is a product and artists have rights.