If that happens then the crew on the spinnaker boat is not doing their job right. If both are sailed equally well then the A has nothing on a spi boat.

Overhere they don't even start the A's on the spi course anymore despite the fact they reach the A-mark ahead of the fleet on the first upwind leg. After that they get overtaken by the fleet anyway when they're sailing downwind high when the spi boats are sailing fast and deep. Makes for dangerous cross-overs as they tend to creep up on you behind the spinnaker.

Additionally, sailing an A-cat very well downwind (=wildthinging) is a skill that is harder to learn then sailing downwind under a spinnaker.

That is just the way it is.

Wouter