I just made a simple comparison between two food types, on the one had the example OP gave (doritos), and on the other hand the most common staple foods eaten in the world, like grains and legumes.
Again if I have to repeat that, the most common staple foods in the world.
That I hope does enough to dissuade you from making the argument that eating these ingredients is a ridiculous endeavor. It's actually what the majority of healthy humans eat on this planet for centuries, the standard, the norm.
It's for anyone obese to figure out why they don't apply this norm.
Take legumes for example, cooked as a Daal it is eaten by more than a billion people all the time. 20 to 30 different types of pulses are cooked, and hundreds of recipies exist. If you walk into your local Indian restaurant, you'll experience a wide range of intense flavors. To say these are the blandest ingredients is incorrect, virtually everyone would prefer to eat such food daily compared to doritos for breakfast, lunch and dinner.
The idea that ultra-processed foods are a staple in my diet, is insanity. I'd be disgusted. I love ultra-processed foods as an occasional snack, not as a diet. My diet is healthy, affordable and tasty. Google and youtube are full of examples of affordable, tasty meals.
Minimal processing is completely fine by the way. There's little wrong with a good canned bean for example, great shelf life, minimal salt, maximal convenience, good nutrition, good price. Thrown into a salad with a simple dressing of olive oil and lemon juice, with some cut vegetables, gives a complete meal. Not more expensive than doritos, healthy, full of vitamins, calories, low glycemic index, protein, and 'cooking' is a matter of throwing the ingredients in a bowl and mixing, childs' play.
Same with the daals I mentioned, mostly a matter of throwing ingredients into a pot. Cooks itself with no supervision in less than half an hour while you're on your phone. Stores 5 days in the fridge or months in the freezer. Can be a great breakfast or dinner multiple times a week.
There's just tons of these options that are delicious and easy, cheap and quick, enjoyed by billions. Obese people just need better education and mentorship in my opinion. I could never be fat because my parents and environment showed me normal food culture, without it I'd probably be fat. I truly believe in the power of mentorship here, which isn't properly institutionalised or commercialised, which is why so many people lack it.