Yes, this has happened to me more than once with Iberia, ex-Madrid, ex-JFK and ex-ORD, so not limited to Santo Domingo / drugs. In at least one case I strongly suspect that the flight was oversold (went out full) and the airline was looking to bump passengers without compensation.
In another case I was literally sitting on a Delta flight on the tarmac while my family was checking in for another, Iberia flight. After lots of back and forth the airline let them board when I sent photos of my credit card (always a good idea!) and spoke to the agent on duty.
Schultzois’ strategy may be a pain, but perhaps necessary.