It basically means 4K 240Hz will need DSC (Display Stream Compression).
You know, for all those people using a $549 - $599 GPU with a $1500 - $3000 monitor. I think the vast majority are going to be fine
Incidentally expect this to become a thing now in some Nvidia biased reviews. AMD DP2.1 has been doing 54Gbps for the past few gens now. Nvidia supported up to 48Gbps on the 4000 series. As such DP bandwidth was not “important”. 5000 series now support full 80Gbps, so expect Nvidia marketing to make this a vitally important point all of a sudden.
This happens regularly where so called “priorities” flip entirely depending on if you are team green or team red.
Conversely, you will now notice that excessive power draw is/isn't important or worth mentioning depending upon your new “priority”.