Stupid is as stupid does. Most electronic AP users are also not dumb enough to try it. People electrocute themselves on their inverters - does that make non-inverter people smarter or safer?

An electronic autopilot steering in no-drift mode or to a waypoint can actually be a safety system in bad weather, high leeway or currents around reefs.

The problem with vanes catamarans has little to do with speed, although the quick response of cats rapidly moving the apparent wind around is an issue. The big issue is mounting in free air. There is simply no good mounting points and no way to get clear airflow to them. I know of one cat who mounted twin Monitors - one on each hull. It never worked for him. It might work on a Warram catamaran. A vane with rudder won't work either because the twin hulls of a cat have them riding on rails. A central rudder would have to be very large and beefy to steer. There is also the issue of running lines and overcoming the increased forces of moving twin rudders separated by 20+ feet of mechanical steering components.

I also know at least one windvane that has broken

Mark