That was from a fear of food poisoning from it being left out in the sun to warm. But it was more of an issue if real mayo, (with raw egg yolk), was used. If you used some type of industrial grade Miracle Whip untainted by anything real you could ID as an ingredient, it was far less of an issue.
Besides, what’s a little e.coli gonna do? Besides make you all shiny clean on the inside.
You know, being 1/2 Korean and 1/2 typical white American I can say y’all shouldn’t be sleeping on potato salad. You can use other and additional ingredients than mayo. My Korean family fucking loves my white family’s potato salad.
As a Midwesterner, potato salad is made with a mixture of real mayonnaise and yellow mustard. Finely diced onion and celery with a dash of old and flavorless paprika for color to round it all out. Salt and pepper to taste. You wouldn’t want it to be too spicy you know.
Some heretics will add diced dill pickle on occaision - my one Grandmother would sometimes do this after drinking too much. This is generally considered a social faux pas, though us Mid-westerners are too polite and kind to actually say something about it. But we will look askance at you. And your children will never play with our kids ever again.