wrong - not just out of order, but leave letters off, substitute the wrong vowels for example, or even better use the wrong homonyms. Then see if the above passage is still readable. I would contest it would be significantly more difficult to comprehend.
I've seen this before, and it is quite interesting.
As a side note, a recent newspaper article reported on the number of 'cartoons' that Ben & Jerry's Ice Cream company produces in a year. While Ben & Jerry was a cartoon, and 'cartoon' is only one letter away from 'carton,' the two words are obviously not interchangeable.
Spelling does matter. Would you want to know your pharmacist filling that prescription doesn't know how to spell, or doesn't think it's important to get the name of a drug EXACTLY right?