Because you can perfectly understand it even though it should be gibberish, this is why people who say "What" after you misspell something are just bullstuffting.
You do realize that if you actually mixed up all the letters in the words it would be exponentially harder to read?
For the image you posted, here are the stats:
Total Words: 16
Unscrambled Words: 7
Words with an edit distance of 2 or less: 13
Max edit distance: 4
Only 3 words don't have 2 letters switch around.
Only a max edit distance of 4 is really small, aka you only need to substitute 4 letters around to get the original word.
Anyway it's not an optical illusion, human brains are just good.
I have seen it before on the forums, basically it goes like this.
"Just wtached an awesome video."
Common response:
"Wtf does 'wtached' mean, what are you trying to say."
They're making fun of that person
