Spellchecking software that would start at zero, and adapt to your idosyncratic spelling as you use it. Eventually it would start correcting "a lot" to "alot" if you used it incorrectly enough. Autocorrect is innocuous enough that you probably wouldn't even notice these negative corrections as they happen
Why It's Awful
This is clearly awful, right? This is a thermostat that turns the heat up the hotter it gets in the house. A negative feedback loop.
It would be nice to see how people's spelling evolves in a vaccuum. For example, I would eventually forget that the word "vaccuum" has two of every letter in it twice and start typing "vacuum". And no one would correct me! It's easier to live in a world where you're always right.
Easier still, is to live in a world where your always right.