That´s not quite true. The enneagram doesn´t cover the differences, but some types are more introverted, others more extraverted. Riso and Hudson figured out the following tendencies:I do not think that enneagram makes differences between intro- and extroverted.
8, 7, 3, 2, 6, 1, 4, 9, 5 (from the most extraverted to the most introverted)
It makes sense. The most extraverted are the types of the assertive group (8,7,3), the compliant group (2,6,1) is following, and the most introverted are the withdrawn types (4,9,5).
The basis fear of eight is of being controlled, therefore they try to control and dominante their environment, so no one can take advantage of them. Eights value their strength and despise weakness. Why do you think the first sentence is wrong?If you look for example in the wikipedia Enneagram of Personality - Wikipedia, the free encyclopedia, even the first sentence about 8's is wrong.
Eights do not want to be in control.