WTFluff I'll bite.
(1) What a wordpress blog shouldn't be used for is for advertising, as a spam generator, or as link bait to drive up hits on blogs the same bloggers have established at other blog sites. In fact the blog will be "discontinued" if you violate this rule.
(2) What a wordpress blog shouldn't be used for is to emulate or extend the scope or social community of a myspace blog, or livejournal or well, ... you do get the picture, right?
(3) What a wordpress blog should contain is actual content written by the blogger(s) in question as opposed to scraped material and video embeds of cats on treadmills or photos of large breasted women.
*LOL* remember you asked for it.