I agree that tactically, this type of maneuver (sharp luff by the leeward boat) almost never makes sense for the reasons stated above. Unless you're in a situation where you have to stay ahead of that particular boat, you usually just end up both losing ground.

However, the leeward boat is not limited to sailing her proper course in this situation. The windward boat must keep clear and should anticipate that the leeward boat may try to defend her position by luffing. This is a basic windward overtaking leeward situation.

sm