On the scalability issues of onboarding millions of LN mobile clients

Keagan McClelland and others have pointed out that the RPC interface in Bitcoin Core is not ideal as it exposes functionality that is not necessary. Additionally, there seems to be a demand for something in between a peer interface and an owner interface that would allow for low-cost ways to serve peer services without giving full administrative access to the node. One idea proposed is to have three ports for a full node: the consensus bitcoin protocol, a wallet services protocol, and a control interface. The wallet services protocol would add additional functionality such as bloom filtering, compact block filters, and output and address indexes for Electrum-like support. The control interface would be the existing JSON-RPC interface without all wallet-related methods. By using separate ports, various middleware could be added to support different authentication and transports.