The problem is that the cost/benefit of creating lists & circles isn't high enough.

Many developers obsess over the edge-case of "how do I post secret information that is only shown to the correct list?"

When in fact, normal people just want to post "Going to Aunt Edna's tomorrow!" to their family list, because it's irrelevant to non-family.

It seems Facebook agrees, with their loosey-goosey smart lists.