It was there from the first iteration of spelling a long time ago (the first iteration was just looking at misspelling frequencies, second iteration 12 years ago moved to understanding multiple spelling mistakes/mistypes)
If you see these kind of easy-to-correct mistakes, it probably means that the spell corrector wasn't given that big attention in the past 10 years.
If you see these kind of easy-to-correct mistakes, it probably means that the spell corrector wasn't given that big attention in the past 10 years.