Java EE (Java Enterprise Edition) General Discussion

When using "jsp:include", tutorials often recommend flushing:
<jsp:include page="myPage.jsp" flush="true" />
The documentation says this would flush the response buffer before starting to write the included page.

But why is this important ?
If you don't flush, isn't it true that the included page will keep writing into the current buffer, and flush it when it's full ? What's wrong with that ? That even sounds more efficient....

Thanks :)