[mcrittenden]

Is there any compelling reason to use tmux if you're already using a tiling window manager?

[caipre]

Persistent sessions is a nice feature.

[Goranek]

when you're using ssh/mosh

[andyl]

Detached sessions on remote systems.

[oftenwrong]

If that is the only reason, one could just use dtach instead.

http://dtach.sourceforge.net/