Why is it that no maker ever gives advice on what to do
if your pocket digital wonder gets accidentally immersed
or suffers a spillage?

It's common knowledge in the electronics industry that if the "soiled" item
is thoroughly flushed in/with distilled water, then allowed to dry (or
forcibly dried), it will often recover. If the manufacturer advises the
consumer to do this, and the device remains dead, the manufacturer could
find itself liable for a free replacement. * In many cases, a customer could
visit the nearest cell phone store and get a replacement in less time.

Nikon once ran an ad about a photographer in India who'd accidentally dunked
his F. He carried it some distance in a bucket of fresh water (which was
then standard for photo equipment -- you kept the camera wet until you got
it to a service tech), periodically removing it to snap a shot! (It's not
clear how the film survived this treatment.)

Almost 30 years ago, while on a canoe trip, my Olympus XA got completely
immersed. I immediately bought another one, but I discovered -- several
years later -- that it still worked! And it still is working! It didn't rust
or corrode. Amazing. Structural plastics -- ya gotta love 'em.

* About 15 years ago, I took my HP 4M into work, because we were doing so
much printing there weren't enough printers to go around. (The company later
bought me a replacement toner cartridge.) As I was carrying it out of my
apartment, the paper tray came loose and crashed on the concrete steps,
breaking. This was around the time of a major California earthquake, and HP
had run an ad telling how another model of laser printer had fallen to the
floor without damage. I pointed out that HP couldn't very well use this fact
as an inducement to buy their products, then object when I asked for a
replacement tray that had been subjected to similar abuse. After some
haggling, I was sent a slightly used tray at no charge.