A label, in the thin sense, is a sticker. You could replace it and the thing would remain. Human naming is asked to do more. We teach a child a name so that the child can call for the thing, ask about it, distinguish it from what it is not, promise it, thank for it. We argue about names because a bad name will send the mind to the wrong object, or to no object.
Watch what happens when someone says “never mind the words, look at the thing.” He is still using words to point. He has to. You cannot hand someone the world. You can speak, write, draw, and number — and drawing and numbering are already kinds of saying. The instruction to skip the name is itself a name for an act, and it works only if the hearer already shares enough speech to know where to look.
If words were only stickers, teaching would be impossible. A lesson is not the transfer of an object from one mind to another. It is speech in which two people come to mean the same thing by the same words, well enough to go on. When that fails, we do not say “they have different stickers.” We say they have not yet understood.
There is an exact answer to why a name cannot be a sticker, and it is not this path’s job to give it — a path grants what is true in an objection and shows the cost. But the answer is not being withheld. It turns on what kind of sign a word is and what kind of sign a concept is, and the foundation pages give it in full.
The account of words, concepts, and things is in the foundation, at How a word reaches a thing, What kind of sign a word is, and One name, many things. It is drawn from Aristotle and Aquinas, with Walshe, Andres, Houser, and Maritain as guides. One question there is left open — how the concept is formed as an inner word — and the pages say why.