I find track folders useful for three reasons.
Suppose you put all your background vocals in a Harmonies folder, all your drum tracks in a Drums folder, all the guitar tracks in a Guitars folder, etc.
1-You can mute or solo (or archive) everything in a folder at once. For example, if you just want to listen to the drums for a moment, you don't have to solo each drum track: just solo the folder.
2-As mentioned above, if you are just working on certain instruments (like the guitars), you can collapse the other folders so they are not taking up room on the screen. With some consoles (like the VS-700) you also won't see the faders for the collapsed tracks which makes it easier to focus on the group you are working on.
3-You can rearrange your tracks just by moving a folder. For example, you can put all the drums at the top, then the bass, then all the guitars (or however you like it) just by dragging the folders. I have a sepcific order, but it may not mean anything to you. People who worked on large analog consoles with tape machines usually have some order of tracks burned into their brains.
I usually put whatever is in a folder in a separate bus, but that's a separate discussion.