I'm not sure about how atomics having the performance of loads mean they will scale (and to be honest i doubt they could have the perf of loads on modern architecture, otherwise why would e.g. Intel not implement them to be faster - but lets pretend it is possible)

The fine article shows that a single lock xadd can destroy perfs on some x86 systems and explain that it is due to cache line bouncing. You would get the same effect with loads: if the loaded data is RO or mostly RO it will of course scale fine. It won't scale as soon as it starts bouncing too much.