It was able to, but it was not especially efficient at doing so, to some extent because the hardware platforms themselves were not scalable and only appeared to

It was able to, but it was not especially efficient at doing so, to some extent because the hardware platforms themselves were not scalable and only appeared to be so because of brute force (even e10k is essentially shared bus SMP machine, sun4d-style). In fact, the NUMA support in non specialized systems (one would want to say "non-IRIX") is surprisingly recent development. In Linux it is one of the things that happened in the 2.4/2.6 timeframe, which is the same timeframe when mainstream distributions started to be too bloated for lot of old or underpowered hardware.