For
Some people have allergies or special diets.
Against
It can be disrespectful to the business and its chefs.
Anonymous excerpts, translated where noted.
“Bringing your own food is brilliant!!”
“Restaurants don’t mind after I explain I have a tricky allergy.”
“It really isn’t acceptable to bring your own food to a restaurant.”
“Restaurants don't allow you to bring your own food because that's literally their business, plus it's rude.”