It would be useful to to make certain tracks in the arrangement as always globally visible on top, like other global tracks (marker/tempo tracks etc.), so that even when you scroll way down in arranger window, you will always be able to see those tracks at the top in your arrangement.
Off course this behavior should be a turn on/off toggle behavior for each individual track.
Examples of why this might be a useful feature :
Example 01 - If you sketch out a piano idea and want to convert it to full orchestral arrangement. It will be useful to have the piano track, as a reference always visible on top while you work on orchestrating for strings/brass/woodwinds etc.
Example 02 - If you want to use an Empty instrument track as an additional marker track, by using events of the instrument track as individual markers, typically while scoring to picture (but not limited to it), you'd always want it to remain globally visible on top like other global tracks.
These are the 2 things i would typically use this feature for, but I'm sure you guys might find other imp uses of this in your personal workflows.