I think your question is perfectly justified, when I read that part first, I was just as puzzled as you about what the Wikipedia author meant (I guess after. After reading it 3 times, I think got it now, and if you ask it as a question, I would probably write an answer. (Hint: if you think of "dependency" not just as the Service class itself, but as a library which contains that class and additional infrastructure code, then part 2 & part 4 may start to make sense).
IMHO it looks like a good question for our site, it is focussed, it is about a topic (DI) which is discussed here on this site very often, and it is most probably not a duplicate of an existing question. It also shows the effort you invested to answer the question by yourself.
However, I can speak only for myself, some people in the community seem to downvote and close everything which smells a little bit like a request for discussion. They may mistake it for a "discuss this blog" type question. I don't share that point of view, since I think the question is perfectly answerable. The only way to find out is probably to ask and see what happens,