We've had spellcheckers for decades but I find it really surprising that automated grammar and proofreading checkers aren't in common use yet. For example, having my email client highlight overly long sentences, duplicate words, ambiguous references (e.g. what noun does "it" refer to) and more would undoubtable save proofreading time and doesn't sounds that difficult to implement. I see online comments every few days of someone pointing out the word loose/lose is used incorrectly for instance.

I recall that many grammar checkers suffer from false positives though but has the technology not advanced?