Even if the Sequences are linearly ordered, you can read them in any order, so linear ordering allows all readers to choose what they want.

On the other hand, if someone has decided to spend a lot of time reading it all, it is frustrating when the recommended reading order is not obvious. For example in the list of Sequences, major sequences are listed before minor sequences, but at the same time it is recommended to read "Map and Territory" (a minor sequence) first. So... why aren't these things just listed in the recommended reading order? The distinction between major and minor is either unnecessary, or could be shown e.g. using some icons near their titles.