I don't think anyone made dressing/stuffing that wasn't inside the bird back then.
To the Internet!
Wikipedia said:
It is not known when stuffings were first used. The earliest documentary evidence is the Roman cookbook, Apicius'"De Re Coquinaria", which contains recipes for stuffed chicken, hare, pig, and dormouse. Most of the stuffings described consist of vegetables, herbs and spices, nuts, and spelt (an old cereal), and frequently contain chopped liver, brains, and other organ meat.
Names for stuffing include 'farce' (~1390), 'stuffing' (1538), 'forcemeat' (1688), and 'dressing'. After about 1880, the term stuffing was replaced by dressing in Victorian English.
“A lot of people will say that ‘stuffing’ is cooked inside the bird, and ‘dressing’ is served alongside,” says Rebecca Hays, managing editor at Cook’s Illustrated. “But I don’t think there’s technically a right or wrong answer.”
The inside-outside theory does fall apart quickly. Hays says her New England-based magazine uses “stuffing” whether the dish — usually some blend of bread laced with seasonings, vegetables, maybe meat — is cooked inside or outside the bird.
Slip below the Mason-Dixon line and the terminology flips: it’s always ‘dressing’ regardless of how it’s cooked.
“It’s ‘dressing’ whether it’s in the bird or not,” says Jean Anderson, author of “A Love Affair with Southern Cooking."
Then there's the regional variation of the ingredients, which I'm sure also accounts for some of the differences here. Traditional north-eastern stuffing is made with hearty white bread, while southern stuffings often employ cornbread. New England uses onions, celery, thyme and sage. Oyster's are included in many coastal communities. Midwesterners like using rye or dark breads like pumpernickel. Sourdough is popular in northern California along with wild mushrooms. There's even tamale-based Thanksgiving stuffings found in Texas with pork, chilies and raisins.
Then there are variations among southerners.... rice is popular in the Deep South and Carolina Low country. Cracker crumbs and biscuits are used in some areas, and where pork is king you'll find ham, bacon and sausage in the mix. In Louisiana you'll find more rice in stuffings along with andouille sausage, tasso and hot peppers providing a Cajon/Creole influence.
So regionally, pretty much everyone in the south (mostly south of the Mason-Dixon) and some in the midwest call it "dressing." To everyone else, it's just stuffing.
Now, someone mentioned that using the term dressing may be born out of politeness - as I quoted in Wikipedia above, "dressing" seems have overtaken "stuffing" as the preferred term in Victorian English around 1880. That may why dressing still rules in the south:
“‘Stuffing’ was not a pleasant word,” says Eve Felder, associate dean at the Culinary Institute of America, who grew up in Charleston, S.C. “So you always called it ‘dressing.’ It’s like ‘grits’ was not a pleasant word. So even though we lived on grits, we called it ‘hominy,’ because it’s a gentler word.”
Personally, I don't think that stuffings were cooked outside the bird until Stove Top stuffing made an appearance, probably sometime in the 1970's.
Many chefs and the USDA do advocate cooking stuffing outside the bird now. Food safety is part of the reason, but the other is that when the bird is done cooking, the stuffing may not be - leading to either a potentially unsafe stuffing, or an overcooked bird. But, getting it back in the bird is becoming more and more popular now.
I don't do it because I don't want anything standing in the way between me and a perfectly cooked turkey.