It doesn't have anything to do with punch cards, it's to pack as many elements as possible into the very small amounts of memory on PDP-11s. A 16 byte directory structure (which divides evenly into a disk sector) with a 2 byte inode number and an up to 14 byte name is a memory-optimized structure, and memory optimization drove everything on UNIX. (I've been programming since 1965, used punch cards for a decade, was a UNIX V6/V7/PWB kernel and userland developer for a different decade).
I know the guy said "harkens", and I pointed out that it's wrong (but maybe he doesn't understand what it means, and thinks it's the same as "reminds me of"). Fixed size fields both precede and follow punch cards ... they are still used today in every struct.
