> An artist that paints something that I can't distinguish from a Van Gogh is a very skillful artist and the painting is very beautiful.

There are a lot such artists who can do that after having seen Van Gogh's paintings before. Only Van Gogh (as far as we know) did paint those without having seen anything like it before - in other words, he had a new idea.

So, if we apply to software, should we quote Dijkstra each time we use his graph algorithm?

Should we also say "if you can implement Dijkstra's algorithm" it's irrelevant because "you did not have the idea"?

It's great to credit people that have an idea first. I fail to see how using an idea is that "bad" or "not worthy", ideas should be spread and used, not locked by the first one that had them (except some small time period maybe).

Even the mechanical skill of painting gets a lot harder without an example to look at. Most people can get pretty good at painting from example within a year or two but it’s a big leap to simply paint from memory, much less create something original.