I came up with this idea when I was using protonmail. In protonmail it is possible to organize emails in your inbox using a system of tags and folders.
I realized that tags are mutually inclusive and infinite, and folders are mutually exclusive and finite(the max amount of folders is the total amount of items if you have one item in each folder). It is my hypothesis that tags are only useful in combination with folders, yet folders are useful on their own because they partially accomplish the function of tags.

Is there any objective way to evaluate this situation, maybe even using formal logic? This is a college dropout who has limited math education asking.

pic related shows a newer version of protonmail where they call tags "labels, and it's harder to see that the tags overlap and are mutually inclusive.