"Suppose instead there's 100 doors, 1 car and 99 goats. Suppose you choose door 1. Then the host opens doors 2, 3, 4 ... 56, 58, 59, ... 100. So there's exactly 2 doors closed, door 1, which you picked, and door 57, which the host decided not to open for some strange reason. Would you still claim that there's no benefit of switching from door 1 to door 57, that it's still 50/50?"
What would prevent the car from being behind door #1?
Say, you were the host, and door #1 actually had the car, as the host you would still have to randomly choose one of the other doors even knowing that there would be a goat behind it (both doors would have a goat)
Before the host opens the doors you would have 1 in 100 odd of choosing the prize. After the door openings you would have a 50-50 odd of choosing the door with the car (ie door #1 + 57 would both have an equal chance of having the car..... ie no benefit)