You have found one of the prime schisms in the character of ICANN -- the
question of "What is an SO?".
The answer is found in the history of the ICANN drafts including the
process under which they were created.
First off, they were created by a closed group, in private, with no public
interaction over the issues or solutions. The prediliction of the
drafters for closed process and control of the larger by the smaller was
carried forth into the contents of the drafts.
The drafts as they came out were uniformly of the nature "strong/dominant
SO vs nearly nil board of director powers".
The outcry against that format was very significant. As a result the
structure was able to be nudged slightly towards "not-quite-so-strong /
not-quite-so-dominant SO vs not-quite-eviscerated board of director
powers".
(Remember as it stands, SO's still direct ICANN policy, the board has only
the thinnest of grounds to stop an SO initiative.)
So what you are seeing in that statement about SO's being advisers is
nothing more than a fig leaf - but it doesn't even begin to cover up the
fact that the SO's are still "the" source of policy and power under ICANN.
--karl--