The explanation for outer deadzone doesn't make any sense.
Deadzones exist to minimize the "drift" or "slow turn" that occurs with worn/faulty hardware. If your controller is perfect, deadzones are not necessary.
You're misunderstanding...
what you described refers only to the inner deadzones (to avoid drift), however the outer deadzones are designed to get you to the pegged state (fast turn) sooner - allowing you to peg without quite as much thumb movement / effort.
hence why some people might really enjoy having a generous outer deadzone.
not sure if I explained any of that any better - but does that makes any more sense?
my fingers are messed from years of piano, cooking, and home renovations - so I've been on a 0 inner, and bigger outer deadzone and my tendons have been much happier.