Why does the iPhone have a physical sound-switch? I'm new to the iPhone world, although I've been down iPod lane for a few years. One thing that is well-known (and even parodied) about Apple devices is the slimmed down and minimalist approach.

So it strikes me as odd that there's a dedicated switch on the side, just for silent mode.  There's already the control center for many similar 'quick go to' things, which also includes 'do not disturb' (which in turn doesn't seem that different to me). 

So what's up with the one-function switch on the side?
The late Mr. Jobs felt it was essential to be able to mute a cell phone without pulling it out of your pocket, and/or in the dark, with minimal light disturbance, without having to hold it up to see it, without being distracting to the reason you are muting the phone in the first place. IIRC, he actually described something to this effect at the original iPhone unveiling 29 June 2007