The problem is, additional electrodes tend to block side and vertical flame propagation.
The more obsticles between the spark and the fuel charge, the more the fuel charge is shielded from the ignition source. Think of a large room filled with explosive gasses. What is the best way to get the most energy production, the biggest bang? It is with an unobstructed ignition source suspended in the center of the room. If you place a small wall near the ignition source it will reduce the explosive energy a bit because it shields some gas behind that wall. This shielded gas will ignite late costing power production.
As you add more walls to the side and above the ignition source you're going to compound this problem. That is why a single negative electrode spark plug has been around so long. It doesn't look nearly as cool or trick. But in a well running engine, it does a better job.
Where a multi-electrode plug usually excells is in the area of mis-firing. With more options, the spark is more likely to fire every time under adverse condtions. If your engine tends to foul (too much oil consumption, for example) these may help. But you're putting a band aid on the real problem or oil in the conbustion chamber. If your spark is weak these plugs may also help. But it's far better to correct the condition creating misfire and installing the right, single electrode spark plug.