Better question: why would anyone spend a large amount of effort in writing a post that takes ideas from another source, only to subsequently not mention to source even though the core parts are taken word-for-word idea-for-idea?

Intellectual dishonesty is not difficult to detect. Unless you're an idiot or if you have already absorbed the knowledge fully (and thereby transformed it into your own unique idea), it's never a bad idea to say, "taking from the ideas of <author>, ...," so I don't expect anyone to sympathize in this situation.