Business is all about gaining fair or unfair advantage over your competitors and no one knows it better than Apple. Take a look at Section 3.3.9 of the iPhone developer agreement, it says right there;

-          Either you or your applications may not collect, use, disclose — user device related data, to any 3^rd parties. Unless and until a prior notification has been made, you are supposed to follow these conditions.

First off, these terms hardly ban advertisements and nor do they place a blanket on the collection of analysis related to users. Apparently, the Section 3.3.9 directly points to the iAds incident where Apple warmly extended an invitation to all Ad companies to make use of iPhone applications, in order to advertise their stuff on it, but there was one condition and that condition has been stated above in this article.

To think of it, there may be a number of factors as to why Apple is so reluctant on letting go of user related information out of its hands. First off, Apple is arguably the most trustworthy vendor out there who really means business when it comes to keeping user privacy, private.

Secondly, in accordance to the first reason, Apple is partially willing to let go of some user side information, if the next Ad Company promises on not letting go of that information towards some 3^rd company.

Does that sound anti competitive to you? Perhaps yes, but it is always better to be secure about things, rather than being careless or way too open about them.