Multicast may well be shitcanned to an expensive slow path, given that multicast is rarely used for high bandwidth scenarios, especially when multiple processes need to receive the same packet.
With multiple processes listening for the data? I think that's a market niche.
In terms of billions of devices, multicast is mostly used for zero-config service discovery. I am not saying there isn't a market for high-bandwidth multicast, I am stating that for the vast majority of software deployments, multi-cast performance is not an issue. For whatever deployments it is an issue, they can specialize. And, as in the sibling comment mentions, people who need breakneck speeds have already proven that they can create a market for themselves.
