See the following FAQs:
Because there's more explanatory information on the help pages. Also, this way they know that there are help pages that they can consult to find additional information.
Was it really necessary to resurrect a 2-year-old thread for this?
It's a tradeoff. My answer was more useful then, but may become useless some day. I think that's better than a less informative answer that works forever.
I could have gotten the best of both worlds by copying the help pages in their entirety into my answer, but that's more work than I felt like doing.
I'm volunteering my time here, I think it's presumptuous of you to give me a hard time because my style of answering doesn't meet your standards.