I've been using analog mixers in my setups ever since I started with music production.
No fancy studer, ssl, or neve consoles, just a box with lots of inputs, outputs, and routing options.
I find having every synth, effect, or drum computer accessible by just opening up a fader is such an incredible time saver.
The option to sum multiple inputs and record with effects is something I simply can't live without.
I just bought a Mackie VLZ4 16 for live performances. There's no time to scroll through menus in a live situation. I need to find my kick drum in a fraction of a second. Actually, building up muscle memory to blindly know where to find each instrument is one of the most important things, in my opinion, for playing live.
Dub mixing is also something I'd love to do, just add a delay and reverb on a send, return it to a channel, and create feedback loops. You can do this with any analog mixing desk.
Do you use a mixer in your live or studio setup? Why or why not?