Wow, this is actually funny! I wonder how many Merc owners there are out there that never realized that the knob is an "all-in-one" design, just like the tiller. ;D
In truth, I remember figuring it out by accident too, many years ago. It bothered me that the writing wasn't right-side-up, so I tried to spin it and noticed that it did more than just rotate.
Oh, and one more thing, just so you know - The throttle adjustment isn't instantaneous like with the tiller. It'll take a couple of seconds after you turn it for the change to take affect.