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).

No, can't apply the same reasoning to software, because the other is art, and hence tied to emotion, taste etc.