Or derbies, bluchers, or ...
For what it’s worth, I’m a ‘baby boomer’ who grew up in the American northeast, and I dressed in the usual prep-style when in high school. I certainly had a pair of penny loafers back then, though neither I nor any of my classmates wore them without socks as far as I can recall, and I don’t think I wore them with a suit either (though I rarely wore suits back then anyway).
That said, I don’t think I’ve owned a pair of loafers since I was in my 20s.
As an academic I suspect I’m part of the ‘eastern establishment’ by definition, if not, perhaps, as firmly entrenched a part of it as I would be if I were, say, a banker.
There's a lot of regional diversity not only with regard to whether or not one should wear loafers with a suit, but also whether or not it's appropriate to wear them without socks. In my experience loafers without socks aren’t all that unusual in Italy in the summer. I’ve also been told that they’re commonly seen in the south of France as well. I can’t testify from experience regarding the latter, though I’m sure that others here, @EFV perhaps, can. Out of curiosity, how do people feel about the sockless look?
When wearing loafers with a jacket (suit or odd jacket) I always wear socks...but there are summer occasions with a linen shirt for example where loafers sans socks are worn.
But then you are getting into different styles of loafers. I would never wear a cordovan loafer sockless...whether tassel or penny. But a pair of Italian styled loafers without socks in a relaxed environment is acceptable. I also wear a pair of navy gucci horse-bit loafers (goodness gracious what a confession!) without socks in the summer...but I'm not one of the many men who wear their black gucci horsebits with their suits every day of the week.