One of the reasons we needed extremely aggressive unrolling was the size/lack of a stack, making recursion or anything that might look like it difficult/limited

One of the reasons we needed extremely aggressive unrolling was the size/lack of a stack, making recursion or anything that might look like it difficult/limited/impossible, due to needing to store a location to jump back to. Anything you could do to minimise the amount of things needed to store, and their size, wasn't wasted time. And though it might very ocassionally be similarly necessary on some chips today, it's more likely you'll work in assembly on those.