This may not seem like a big deal, but consider the effect that such an influential source of “correctness” can have on the general sense of what is correct.

Spell checkers like Word’s are responsible for the “z” in British English being demonised. Once upon a time, according to linguist Gretchen McCullen, it was common in British English to use both z and s. But somewhere along the line, automated spell checkers categorised one spelling as British and categorized the other as American, and it created a whole new hobby for many British people who fancied themselves the guardians of the English language, courageously pointing out whenever someone used the filthy, “dumbed down” version from across the Atlantic. We have these brave volunteers to thank for defending the purity of the famously consistent English language, and for these people we have spell checkers to thank.

Thanks a lot, spell checkers!