Agreed, a lot of grammarians are pedantic for sport. To bring this around, since this is hacker news: the way I think about it is as error correcting codes. For a given sentence, with a certain amount of errors, others can still understand it, but beyond a threshold, you can't (without thinking hard) . The Rules give us that margin for when we make mistakes.

I think this gels with your point about professional environments - as ideas get more complex, that margin for error gets slimmer.