Why Are Some "Social" Sites so Hard to Use?

Why are some social sites so hard to use? Did these people not get the memo about user experience?

It is getting so annoying that I may have to snark about it on Marketing Snark. (I'm sure they live in fear. Not.)

But seriously, if it drives me crazy, and I build blogs all day, it must be driving away casual users in droves. Oh, well. Their problem, not mine.

Oh, wait! It becomes my problem when I have to use those social sites to promote my blogs.

And don't even get me started on the posting/authoring software at Examiner.com. Grrrrrr! (I told you not to.)