If the file is structured like:

## First section

......

## Second section

xxxxxx

There is no overall view of the file to scroll through, just each section. If there is a top level # Main title, then that allows you to browse entire file. Perhaps, regardless of whether there is a top-level header, the first entry in the outline should always be a view of the whole file? Or there should always be an 'Overview' section at the top if there's not a named header? Not sure the best way to solve. Ultimately, not all markdown documents are going to be perfectly organized with structured headings.

Edit: example - I have a table at the top of one of my .md files. That table is never rendered because it's not part of a heading. I have to edit the file in order to view.