Some big.little's have very good interconnect / memory access. Some systems have remote NUMA memory - you are going off one board over an internconnect to another board to memory there.
The headline is so misleading. I could wire together a ton of machines over 10mbs, and yes, I could get NUMA going on it and a high core count, but the performance would be horrendous. Maybe you could even run super NUMA over DB9 9 bit serial ports with remote memory access latency in hours?