I understand it now - it's so you can listen to how a comp
would sound, if it was included into the track, even when currently a different one is selected. But although I can see that usage, it's infuriating for the times when you're trying to listen to the start or end of clips specifically (eg. to be able to make sure it blends well into a different clip), and the soloing means you hear past the end of the section you wanted.