There must be some limiting factor.
I speculate that its one of a few things:
- Keeping the rig pointing into the wind is too expensive. In the 1890's your only choice was a vane of sorts. The very fact that its rotating and using the torque to drive a generator must mean that a significant amount of energy must be expended to tune to the winds position. With a vane design, it would have to be large. Some of the historical patents are showing smaller vanes and some mechanical magic to turn the rig. For an electronic turning of the rig, you would most likely employ some software to average out the eddies and momentary wind changes before turning. A dampening effect if you like.
- Each blade on its own axis may momentarily have some torque that would potentially cause it to jump its own gearing. It might do this because the wind on the individual sail might be uneven left to right. That 2:1 gearing is crucial to success of course, so perhaps even going one tooth different would be enough to require manual intervention. The gears and chains (or axles) might have to be substantial to reduce the chances of cogs slipping. For a design where your using a motor under each sail to turn, you might suffer increased motor stress because of the squalls and eddies of the wind in any situation.