I agree with you about the term "serverless" being silly, especially in a time when all the various forms of decentralized architecture are beginning to come of age. It makes it difficult to find information on "serverless webrtc signalling."

While other auto-scaling PaaS exist, the granularity of the lambda pricing model is fairly new and groundbreaking. A service can be launched that may see very little use and just costs pennies to test out during its initial phases. That same service will scale exponentially rather easily in comparison to a similar deployment on a traditional server.