Just because there is a gap in the objects defining the physical line doesn't mean the OB line suddenly ceases to exist. If you define OB with string tied to stakes, and the string between two stakes gets broken, you haven't suddenly created more IB playing surface.
The problem is, "interpretation" of a rule in the event something isn't clearly defined. You're stating "everyone knew", "if", "gaps", etc, etc. That line of thinking imop, sure it's ok for weekend warrior C tiers, or casual rounds. But when 1000'$ is on the line, any rule that's going to potentially penalyze the player in any capacity... should be clearly documented and if there's a situation where there is no clear definition of the rule, benefit should go the player.
"you define OB with string tied to stakes, and the string between two stakes gets broken"
If that occurs, then the string should be replaced before the next card throws. Period. We have to be more accountable for the sport, especially at the larger events. The money is going to grow, the gravity of these situations if/when they occur is only going to get stronger.