Celiac and lactose intolerance are completely different from avoiding a brand. Both of those are specific compounds, we have laws stating we must list ingredients included in items, and "lactose free" and "gluten free" have been turned into marketing terms,very proudly displayed on a lot of packaging. It's also pretty simple to understand both lactose and gluten, where they come from, and narrow it down to a single ingredient, maybe with a few alternative names, that will cause issues.

You also have a direct response to the things that trigger you. If you make the mistake once you probably figure out what item it is, and don't make the same purchase. That feedback doesn't exist on a brand level. This (for example) peanut butter tastes the same as the other, has the same effects on my body. You have to do ACTIVE research on the brand to find out that they're owned by nestle. These are not equivalent in the slightest.

I would bet money that if I looked through your pantry and fridge right now you have something you didn't realize was nestle. They actively use deception in the form of different brands that don't display the nestle logo in order to hide the fact that it's a nestle item. Again, you're completely disregarding the arguments people are putting forth and actively calling them less than intelligent.