No, it's not just the compression that takes a long time, yeah you do that before you ship. But you have to decompress it as you stream the level in and that'll still take a freakin long time for so much data.
And Carmack's been talking about this tech years ago anyway. He's done serious research and development, went even further than this guy - instead of instancing everything he looked into data compression and fast streaming from storage to build a unique world. They've probably had their reasons to stick with polygons for…
so much assumptions about how game art is created makes my brain hurt. Not having to worry about millions of polygons for every single art asset is actually a perk for the artist, not a restraint. I can imagine a pipeline/game project where making a super high poly asset for every little thing is feasible. I`m sure in CG…