Back when I was a starter in the Newcastle area some athletes asked if it was ok to set up the blocks behind the line, there is nothing in the rulebook so we just let them set up where they wanted, I can remember at least 3m behind the line at times. i was told later they were pro runners.
I was informed a few of weeks back an athlete tried the same thing at a Sydney interclub and the starters would not allow him to do so. Don’t think the rules have changed just some get followed and some made up on the day.