In that Callisto benchmark, Vega and the RX 580 are positioned relative to Turing exactly as their averages were four years ago, if not slightly better. It's the 1080 Ti that's missing some performance, but not much.
I'd argue that's slightly subpar driver support for Pascal instead of a lack of features hampering it.
Also, the game looks fairly good in Lowest compared to Ultra+RT much like APT:Requiem. Am I the only one thinking it's insane to go for 144 fps here instead of, ahem, the cinematic experience?
Well if you look at the relative performance when the 5600XT launched, you can see that during that time, both Vega 64 and 5600XT were actually ahead of the 2060. Vega in general had a lot of driver issues with it's driver which made it under perform not to mention AMD was pretty horrid with DX11 titles. As we moved onto more and more DX12 titles and AMD fixed their drivers, Vega and AMD's arch as a whole benefited hence why you see them increasing their position in relative performance during the 5600XT launch vs their own launches.
But now if you look at the Callisto Benchmark as an example, both the 5600XT and Vega 64 are now behind the 2060:
And also remember that 5700XT was ahead of the 2070 and now that's behind as well:
PC Specs: CPU: 5950X || GPU: Strix 4090 || RAM: 32GB DDR4 3600 || Main SSD: WD 2TB SN850