Yeah, I worked on a startup to push IP multicast TV to consumers way back when. Went nowhere for the reasons you state, but we got some cool tech out of it regardless.

I meant at real scale where it makes sense. You're correct in that your upstream ISP needs to support PIM to the customer edge, which is hard to get, but available for certain customers and especially so in datacenter fabrics.

ah yes, I thought you were talking about distribution rather than inside a production facility. At that case the bandwidth of uncompressed 4K (which you want to do so you're not introducing compression artifacts) is in the order of several Gbps, so bandwidth is pretty high, although multicast is used.