Just see it like this: For a good quality desktop print you need 150 dpi. This means that a high quality jpg of 600x750pixels gives you a postcard.
For offset print you need 300 dpi. So for the same postcard you need 1200x1500pixels, and no jpg is ever good enough for high quality print.
I suppose it's more a question of stealing ideas. But that is in fact a very modern problem as in the fifteenth-eighteenth century painters simply copied one-another. The ego became more important with the rise of reproduction of artworks.
For offset print you need 300 dpi. So for the same postcard you need 1200x1500pixels, and no jpg is ever good enough for high quality print.
I suppose it's more a question of stealing ideas. But that is in fact a very modern problem as in the fifteenth-eighteenth century painters simply copied one-another. The ego became more important with the rise of reproduction of artworks.