Excellent question. I'd say it's "advanced enough" in terms of semiconductor process node, "brute-force enough" in terms of circuit logic. A barrel shifter is definitely one of the most "brute-force" kind of logic circuits - you want to shift many bits in a word, but at the same time in a single cycle? Just use a large matrix to connect every possible input bits to every possible output bits. Early chips simply couldn't afford the die area on this non-essential but nice-to-have feature.