You have not missed anything, there is no shortcut to mute a track, however, I found a solution you might like,if you don't know about this already, when you're on a track just use the right and left arrow keys to make the little white corners appear on the mute button and press enter, (you only have to do this once as long as you are muting and unmuting things) the track can be muted, and unmuted the same way, and at that point you can use the up and down arrows to go to different tracks and the mute button will still be available to just press enter to mute or unmute. Same goes for naming tracks, solo, etc.
for me, MCU pro has that "sliced bread" effect.