Not only for emacs. It's remarkable how much the typewriter (or computer) keyboard exercise the pinky, compared with most other day-to-day activities.
The saxophone too... the left pinky table on a tenor sax is (almost) as much work as the shift key on a mechanical Olivetti typewriter.
It wouldn't be a picnic for vi users either: lots of commands start with a colon character, control character, or <escape> to change modes.
Ditto. I've never wanted to get rid of my pinkie, I always wanted it to be stronger. I'm sure the author would also agree seeing how he broke his.
Guitar Hero on Hard or Expert exercises the pinkie finger pretty well. No joke.
You can get a springy finger strengthener for $10 or so, by the way. I found that after using Emacs for long periods of time I'd get a lot of tension built-up in my pinkie. (No RSI problems in my wrists, but my pinkie was really bothering it me.) Stretching it with one has helped a lot, as has using a typing timer (such as xwrits or workrave).