To be charitable, the argument could be "high-res textures won't be visibly different on 1080p" which is not generally true but at least it makes sense as an argument.
If you can't even store them in vram, you'll have massive performance issues as you fetch them from system memory. Imagine having to go back and forth from System memory to VRAM multiple times to draw a single frame, your framerate will dumpster.
If they are already in VRAM and fully stored, along with their full mipmaps, the performance hit in the pixel copying is much smaller (in fact, it's quite negligeable on modern GPUs).
There seems to be a lot of things you're missing here.
It's not about screen framebuffer (4K vs 1080p), it's about textures. You didn't read his post.
Doom Eternal uses 8 GB of VRAM with hi-res textures.
To be charitable, the argument could be "high-res textures won't be visibly different on 1080p" which is not generally true but at least it makes sense as an argument.
I did not know that high resolution textures don't impact performance significantly as long as you have enough VRAM.
If you can't even store them in vram, you'll have massive performance issues as you fetch them from system memory. Imagine having to go back and forth from System memory to VRAM multiple times to draw a single frame, your framerate will dumpster.
If they are already in VRAM and fully stored, along with their full mipmaps, the performance hit in the pixel copying is much smaller (in fact, it's quite negligeable on modern GPUs).
There seems to be a lot of things you're missing here.