The label is just a tool to help people better understand the principles behind it.
Nobody bursts in a room an announces this stuff, but if you're having a conversation on the subject, it helps to be able to say: "I identify as X, and this is what it means..."
For a lot of people, the lack of having specific words and concise language to talk about the nuances of their identity makes it challenging to express themselves and be understood. The dedicated words and language help affirm these nuances as 'normal'.