Nearly all financial market data is disseminated from market venues via multicast. It's the most efficient way to do it. However, you are right about multicast

Nearly all financial market data is disseminated from market venues via multicast. It's the most efficient way to do it. However, you are right about multicast not being generally used. The consequences of this fact are that there is a limited subset of engineers who understand it well and that vendor hardware support for it is often substandard. We constantly have to provide feedback to Cisco, etc. on what sort of features should be in their hardware and what sorts of instrumentation can help operate and troubleshoot multicast networks.