That's how many it takes to "represent" a neuron. But what does that mean and is it relevant? I haven't checked the original research, but if it means to model the results of a neuron, then it's not relevant (unless you're trying to do brain uploading). Two ANNs with different activation functions will need a lot of nodes to model a single node of the other network, but they have comparable computational power. We don't need to match the neurons to match the computational abilities.