For some reason in my city the tournaments are currently played at 1500 points mark and they enforce the 2k requirements (3+ battlelines), explaining that it's like brackets.
Up to 1000 points: 2+ battlelines
1001-2000 points: 3+ battlelines
2001+ points: 4+ battlelines
That sounds fairly legit, seeing how any other way it'd be 2 battlelines anywhere between 500 and 2000, and this way it's neatly divided into three brackets.