I think mindset plays a role as well. Back in the day, there was a restraint on adding features, at least when they would make the logic more complicated for only a tiny or imagined benefit. Part of that was memory/storage limitations. But I think the pursuit of an abstract idea of elegance was equally important. After all, these systems were primarily written for other computer people.

This idea is completely gone from the world of software engineering. Systems become overloaded with the implementation of every crappy idea under the sun -- if a PM in a fever dream can think of it, and an overworked dev can hack it together, it goes in.