Voted. Only 3 votes? EN loses to Google Docs in that...
>>Why is it impossible?
Because some typical manual usually is a single document. You will give the user in discomfort trying to read many notes instead of one. A document must be read back and forth. If user lost in big text, he always can return to TOC and click any topic.
If the text is long enough, you must provide user some simple navigation. Like interactive or clickable TOC. The navigation anchors (eg. topic1#) is also good solution, because you can use it anywhere in text.