Really, the answer to most 'so many cases of X didn't use to exist!' complaints is that THEY USED TO DIE.
Allergies? Gluten intolerance? Cystic Fibrosis? Seizures? Asthma? Diabetes?
THOSE USED TO BE ALL BUT DEATH SENTENCES.
Y'all ever notice that when people say "There were never that many X people before!!!" X people almost always seem to be Housebound due to Lack of Accessibility or Chance of Severe Illness, Unrepresented because no one Put A Name to the Demographic, Oppressed with Physical Violence and Societal Ostracization, or straight up fucking Dead?? Just me?
on top of all that, people might not have come into contact with the things they're allergic to in the past. or not as much. how would a European person with a peanut allergy have ever encountered the things before American colonization? one of my friends is very allergic to bell peppers, but her Scottish ancestors c. 1700 would probably never see one in their lives. we often have much more diverse diets nowadays
(if it was a mild-moderate enough allergy, they might also just call it an "intolerance" and avoid the thing in question as much as possible. they might not have known why it got them sick, but they could definitely put two and two together)
Also it used to be easier to avoid common food allergens because most people made their own food themselves from scratch, and so contaminants and weird ingredients weren't an issue.
Weird things I've seen in storebought processed food ingredient lists:
Prune juice in flour tortillas (literally why? Tortillas are flour salt oil and baking powder)
Raisin paste in a large amount of cookies not labelled "with raisins" (literally why??? You do not need to put raisin paste in sugar cookies and ginger snaps???)
Corn in literally everything. It's in breads. It's in pretzels. It's in drinks. It's in ice cream. It's in baked goods. It's in candies. It's in potato chips. It's in crackers. It's in sauces and condiments. It's in yogurt. If it's not corn syrup, my #1 enemy, it's corn flour or corn oil or corn starch. Why!!! Is there corn!!! In everything!!!
Soy is also in everything despite being a ridiculously common allergen. Same with peanuts and tree nuts.
It used to be very easy- you say "oh [ingredient] makes me ill" and then you simply don't buy that ingredient or use it with your cooking. Now with most foods being purchased pre-made at the store, it can be impossible to avoid that ingredient unless you make that food yourself from scratch (and even then you may still struggle to avoid cross-contamination from products that should be [ingredient]-free).
Someone like me, with MCAS, would have just died in ye olden days. That's why so few of us existed back then. But someone with easier to predict allergic responses likely would have had a way easier time then than they do now because it would have been a matter of simply not cooking with the ingredient that makes them sick.
Much like when we're forced to go back to work during a global pandemic that the survivors pretend didn't even happen, and keep complaining why no one wants to work anymore.
Well, a lot of them fucking died. Some are now too sick to work. Or some are lucky enough to work from home when the rest of the population acts like none of this happened / is still happening, and take 0 precautions to keep it from spreading.
