This indicates to me that some of the old base models used architectures that were significantly more difficult to run at scale (or to ship around/load differen

This indicates to me that some of the old base models used architectures that were significantly more difficult to run at scale (or to ship around/load different weights at scale) - which is truly saying something, since they were running at incredible scale a year ago. There's probably a decade of potential papers from their optimizations alone (to say nothing of their devops innovations) that are still trade secrets.