They aren't "Just as accurate". What you see with these quants is the providers only ever show performance on already saturated benchmarks. You'll see labs put out 1-bit quants Deepseek v4.1 claiming only 1% degradation because they're only showing the benchmarks which tell that story. Then you look at the performance on those same benchmarks for significantly weaker models like Qwen3.8-27B even and it's virtually the same because that benchmark is saturated.
I like these quants as much as the next guy when they're all I can run but I have both R9700 with 32GB VRAM and a 5060 Ti with only 16GB VRAM and so I run both Q6 Unlsoth quants and ISTA IQ3_XXS quants and yeah there is an absolute world of difference in realworld performance.
IMHO I think it's pretty scummy behavior from the quant providers to frame these quants this way. Just be honest about where the degradation is really occurring on the non-saturated benchmarks.