[detaro]

Some ISP-run and or company/network-internal ones do, but over the public internet there is no infrastructure for that, so the vast majority doesn't do it.

[yusyusyus]

funny enough.. my team probably killed off (one of anyway) the last tier 1 internet multicast deployments over the past few years.

Multicast has dataplane resource scaling issues and, frankly, CDN has become the solution to what multicast solves.